Clarify that this file is not used anymore

vmcj · vmcj · commit 6d98ef218ead · 2025-12-20T17:08:34.000Z
Leaving it there in case someone still builds on GitLab.
diff --git a/docker-gitlabci/build.sh b/docker-gitlabci/build.sh
@@ -1,5 +1,6 @@
 #!/bin/bash -e
 
+# This script is not used in GHA CI
 if [[ -n ${CI} ]]
 then
         set -euxo pipefail
