CLOUDP-226369: Allow backport releases

[josvazg]

• Allow to optionally checkout a back-port branch next to the CI selected branch (current).
• Change the working directory base to current, or backport when doing a back-port.
• Mark chart as NOT latest when doing a back-port.

Tests

✅ DRYRUN release atlas-operator-crds

🟠 Managed to release CRDs Helm chart but did not detect it was released properly.

• ✅ Re-run did nothing as it was released

✅ Regular periodic run does nothing, all charts are already released (keeps working)

🟠 Managed to release the main Helm Chart but it did not detect it as releases properly.

• ✅ Rerun notices it was released

All Submissions:

• Have you signed our CLA?