ci/build: lower the delay to start build-only jobs

What we need is a way to tell GitLab "queue `build-only` jobs after
`build-for-tests` jobs have started", to make sure that `build-only`
jobs don't start before `build-for-tests` jobs and thus delays test jobs
and the overall pipeline.

The best I had found was "queue `build-only` jobs after *all* the
`build-for-tests` jobs have finished", but this introduces a larger
delay than we want, and causes `build-only` jobs to often be the last
ones to finish in a pipeline, after test jobs that respect the 15min
runtime limit.

Instead, we can tell GitLab "queue `build-only` jobs after the
`build-for-tests` jobs have been queued for X minutes", which is closer
to what we want, and in particular this ensures the correct order of
*starting* jobs as long as the CI is not overwhelmed and doesn't manage
to actually start a queued `build-for-tests` job within 5min, in which
case I'd argue we don't care about job order anymore because we have
bigger problems anyway and likely everything's going to timeout.

This also gets rid of the hard-to-maintain `.build-for-tests-jobs` list
of `needs:`, which also needed to be manually merged in half the jobs.

The trade-off is that we need to make a (shallow) copy of the
`.container+build-rules` list, that replaces all the `when: on_success`
with `when: delayed` + `start_in: 5 minutes`. This means that we'll need
to make sure the two lists of conditions remain identical, but this
seems more manageable; nevertheless, I added a comment to remind us.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/33564>

.gitlab-ci.yml

@@ -210,6 +210,8 @@ include:
       when: never
 
 
+# Note: make sure the branches in this list are the same as in
+# `.build-only-delayed-rules` below.
 .container+build-rules:
   rules:
     - !reference [.common-rules, rules]
@@ -266,6 +268,49 @@ include:
     # manually triggered
     - when: manual
 
+# Repeat of the above but with `when: on_success` replaced with
+# `when: delayed` + `start_in:`, for build-only jobs.
+# Note: make sure the branches in this list are the same as in
+# `.container+build-rules` above.
+.build-only-delayed-rules:
+  rules:
+    - !reference [.common-rules, rules]
+    # Run when re-enabling a disabled farm, but not when disabling it
+    - !reference [.disable-farm-mr-rules, rules]
+    # Never run immediately after merging, as we just ran everything
+    - !reference [.never-post-merge-rules, rules]
+    # Build everything in merge pipelines, if any files affecting the pipeline
+    # were changed
+    - if: *is-merge-attempt
+      changes: *all_paths
+      when: delayed
+      start_in: &build-delay 5 minutes
+    # Same as above, but for pre-merge pipelines
+    - if: *is-pre-merge
+      changes: *all_paths
+      when: manual
+    # Skip everything for pre-merge and merge pipelines which don't change
+    # anything in the build
+    - if: *is-merge-attempt
+      when: never
+    - if: *is-pre-merge
+      when: never
+    # Build everything after someone bypassed the CI
+    - if: *is-direct-push
+      when: delayed
+      start_in: *build-delay
+    # Build everything when pushing to staging branches
+    - if: *is-staging-push
+      when: delayed
+      start_in: *build-delay
+    # Build everything in scheduled pipelines
+    - if: *is-scheduled-pipeline
+      when: delayed
+      start_in: *build-delay
+    # Allow building everything in fork pipelines, but build nothing unless
+    # manually triggered
+    - when: manual
+
 
 .ci-deqp-artifacts:
   artifacts:

.gitlab-ci/build/gitlab-ci.yml

@@ -66,41 +66,12 @@
 .meson-build-only:
   extends:
     - .meson-build-for-tests
+    - .build-only-delayed-rules
   stage: build-only
   script:
     - *meson-build
 
 
-# Make sure this list stays the same as all the jobs with
-# `stage: build-for-tests`, except for the windows job as
-# explained below.
-.build-for-tests-jobs:
-  - job: debian-testing
-    optional: true
-  - job: debian-testing-asan
-    optional: true
-  - job: debian-testing-ubsan
-    optional: true
-  - job: debian-build-testing
-    optional: true
-  - job: debian-arm32
-    optional: true
-  - job: debian-arm32-asan
-    optional: true
-  - job: debian-arm64
-    optional: true
-  - job: debian-arm64-asan
-    optional: true
-  - job: debian-android
-    optional: true
-  # Windows runners don't have more than one build right now, so there is
-  # no need to wait on the "first one" to be done.
-  # - job: windows-msvc
-  #   optional: true
-  - job: python-artifacts
-    optional: true
-
-
 debian-testing:
   extends:
     - .meson-build-for-tests
@@ -176,7 +147,6 @@ debian-testing-msan:
   extends:
     - debian-clang
     - .meson-build-only
-  # `needs:` inherited from debian-clang
   variables:
     BUILD_JOB_TIMEOUT: 30m
     # l_undef is incompatible with msan
@@ -280,9 +250,6 @@ debian-release:
   extends:
     - .meson-build-only
     - .use-debian/x86_64_build
-  needs:
-    - !reference [.use-debian/x86_64_build, needs]
-    - !reference [.build-for-tests-jobs]
   variables:
     UNWIND: "enabled"
     C_ARGS: >
@@ -321,9 +288,6 @@ alpine-build-testing:
   extends:
     - .meson-build-only
     - .use-alpine/x86_64_build
-  needs:
-    - !reference [.use-alpine/x86_64_build, needs]
-    - !reference [.build-for-tests-jobs]
   variables:
     BUILD_JOB_TIMEOUT: 30m
     BUILDTYPE: "release"
@@ -359,9 +323,6 @@ fedora-release:
   extends:
     - .meson-build-only
     - .use-fedora/x86_64_build
-  needs:
-    - !reference [.use-fedora/x86_64_build, needs]
-    - !reference [.build-for-tests-jobs]
   variables:
     BUILDTYPE: "release"
     # array-bounds are pure non-LTO gcc buggy warning
@@ -633,9 +594,6 @@ debian-arm64-build-test:
     - .meson-arm
     - .ci-deqp-artifacts
     - .meson-build-only
-  needs:
-    - !reference [.meson-arm, needs]
-    - !reference [.build-for-tests-jobs]
   variables:
     VULKAN_DRIVERS: "amd,asahi,imagination-experimental,nouveau"
     DRI_LOADERS:
@@ -648,9 +606,6 @@ debian-arm64-release:
   extends:
     - debian-arm64
     - .meson-build-only
-  needs:
-    - !reference [debian-arm64, needs]
-    - !reference [.build-for-tests-jobs]
   variables:
     BUILDTYPE: release
     S3_ARTIFACT_NAME: mesa-arm64-default-${BUILDTYPE}
@@ -666,9 +621,6 @@ debian-no-libdrm:
   extends:
     - .meson-arm
     - .meson-build-only
-  needs:
-    - !reference [.meson-arm, needs]
-    - !reference [.build-for-tests-jobs]
   variables:
     VULKAN_DRIVERS: freedreno
     GALLIUM_DRIVERS: "zink,llvmpipe"
@@ -687,9 +639,6 @@ debian-clang:
   extends:
     - .meson-build-only
     - .use-debian/x86_64_build
-  needs:
-    - !reference [.use-debian/x86_64_build, needs]
-    - !reference [.build-for-tests-jobs]
   variables:
     BUILDTYPE: debug
     UNWIND: "enabled"
@@ -744,7 +693,6 @@ debian-clang-release:
   extends:
     - debian-clang
     - .meson-build-only
-  # `needs:` inherited from debian-clang
   variables:
     BUILD_JOB_TIMEOUT: 30m
     BUILDTYPE: "release"
@@ -781,9 +729,6 @@ debian-vulkan:
   extends:
     - .meson-build-only
     - .use-debian/x86_64_build
-  needs:
-    - !reference [.use-debian/x86_64_build, needs]
-    - !reference [.build-for-tests-jobs]
   variables:
     BUILD_JOB_TIMEOUT: 30m
     BUILDTYPE: debug
@@ -820,9 +765,6 @@ debian-x86_32:
     - .meson-cross
     - .use-debian/x86_32_build
     - .meson-build-only
-  needs:
-    - !reference [.use-debian/x86_32_build, needs]
-    - !reference [.build-for-tests-jobs]
   variables:
     BUILDTYPE: debug
     CROSS: i386
@@ -857,9 +799,6 @@ debian-s390x:
     - .meson-cross
     - .use-debian/s390x_build
     - .meson-build-only
-  needs:
-    - !reference [.use-debian/s390x_build, needs]
-    - !reference [.build-for-tests-jobs]
   tags:
     - kvm
   variables:
@@ -875,9 +814,6 @@ debian-ppc64el:
     - .meson-cross
     - .use-debian/ppc64el_build
     - .meson-build-only
-  needs:
-    - !reference [.use-debian/ppc64el_build, needs]
-    - !reference [.build-for-tests-jobs]
   variables:
     BUILDTYPE: debug
     CROSS: ppc64el