Gitlab automerge abort on push: allow turning off

Gitlab aborts automerges in merge requests if new commits are added to a merge request, in line with the description on https://docs.gitlab.com/user/project/merge_requests/auto_merge/#pipeline-success-for-auto-merge

We're running into situations where we would like automerges to not be aborted, for example a formatting pipeline job pushing a format commit back to the MR. If the MR was on automerge before this commit, it should stay that way.

I'd like an option (per-project) to not disable automerge on new commits. The docs state that this happens to ensure the new changes are reviewed, but that seems less relevant: if any kind of approval settings are configured for the project, the merge request will only merge once an approval is actually given, even if automerge is enabled.

An alternative may be to add the push option to enable automerge from the CI job push, if I understand correctly this should re-enable automerge after the commit. The challenge there is figuring out if automerge is enabled.