Handle GitLab upgrade stop versions in backports for db:migrate:multi-version-upgrade

Summary

Identify options on pulling relevant upgrade stops for backport MRs in GitLab repo.

In Tuesday 2024-09-10 17:22 UTC - `gitlab-org/gitl... (gitlab-org/release/tasks#13031 - closed) failing db:migrate:multi-version-upgrade job was blocking backport fix in 16.11. Since the job is using latest_upgrade_stop.gz which is being rotated when new stops and patches for them are released, and at the time of writing latest_upgrade_stop.gz has 17.3.x changes so in backport MR for 16.11 it failed. The unblock solution was to pin the version Pin multi-version upgrade schema to 16.7.6 in 1... (gitlab-org/gitlab!166053 - merged).