ci: drop unused ephemeral packages in alpine image

There's nothing between installing these packages and removing them that
uses them, so let's just drop them.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/25546>

.gitlab-ci/container/alpine/x86_64_build.sh

@@ -9,15 +9,6 @@ set -e
 set -o xtrace
 
 EPHEMERAL=(
-    autoconf
-    automake
-    bzip2
-    libtool
-    libepoxy-dev
-    libtbb-dev
-    make
-    openssl-dev
-    unzip
 )