Make create-branch script more robust in case the jenkins job fails unexpectedly

While trying to create branches for 7.1 jenkins somehow failed me (for both Flow and Neos) and timed out in the middle of doing it's stuff.
See
https://jenkins.neos.io/job/flow-create-branch/20/console
https://jenkins.neos.io/blue/organizations/jenkins/neos-create-branch/detail/neos-create-branch/20/pipeline/

This lead to a couple of things:

• seemingly not all repos had the branches created
• not sure if all post-branch tasks were finished
• jobs are marked as failed, so whoever is looking will see big red dots
• restarting the jobs fails with a push error, because of history mismatch
• unless you have admin access to all potentially affected repositories and know how to "unprotect" branches, you can not progress

So what can we do to make this process easier to recover from in the future?

• check if remote branch already exists, if not proceed as normal
• if branch exists, check if the remote branch is more than 1 commit ahead (git rev-list HEAD..origin/{$branch}--count)
• if remote is more than 1 commit ahead, fail with "YOU CAN'T RESET AN EXISTING VERSION WITH CHANGES, BRO!"
• if it's less, just do --force push and go on, writing a notice level message of "RECREATING BRANCH, DID IT FAIL THE LAST TIME?!"

To check: does the jenkins job have force-push protection overriding rights (is it in the admin group)?

Start by inspecting the create-branch script and the linked Flow and Neos Jenkins job logs, then trace how remote branch checks and pushes are handled. Done means a rerun can recover an interrupted job safely, refuses branches with more than one unexpected commit, and reports the relevant force-push protection behavior.