ci: reorder alpine/x86_64_build rules to fix the nightly pipelines

Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/11400
Fixes: fdd204538b ("ci: build docs using meson")
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/29908>

.gitlab-ci/container/gitlab-ci.yml

@@ -347,9 +347,12 @@ alpine/x86_64_build:
   variables:
     MESA_IMAGE_TAG: &alpine-x86_64_build ${ALPINE_X86_64_BUILD_TAG}
   rules:
+    # Note: the next three lines must remain in that order, so that the rules
+    # in `linkcheck-docs` catch nightly pipelines before the rules in `pages`
+    # exclude them.
+    - !reference [linkcheck-docs, rules]
     - !reference [pages, rules]
     - !reference [test-docs, rules]
-    - !reference [linkcheck-docs, rules]
     - !reference [.container, rules]
 
 .use-alpine/x86_64_build: