Revert "Merge branch 'axil-target-branch-upstream' into 'main'"

Reverts !3430 (merged)

This change introduced an error on the compile_prod step:

NoMethodError: undefined method `match' for nil:NilClass
/builds/gitlab-org/gitlab-docs/lib/tasks/task_helpers.rb:38:in `retrieve_branch'
/builds/gitlab-org/gitlab-docs/lib/tasks/build_site.rake:12:in `block (2 levels) in <top (required)>'
...
ERROR: Job failed: exit code 1

Example job: https://gitlab.com/gitlab-org/gitlab-docs/-/jobs/3588529625

Let's revert this for now.