CLOUDP-373948: Separate CI code from released branch

[josvazg]

Summary

This change makes the release image ensure the workflow uses the CI branch code to release the code:

• The branch to be released foes into released-branch/ subdir.
• The Makefile and scripts/* from the CI branch replace those from the released branch.
• All actions run on the released-branch/ subdir.
• Copies from the released branch to the CI branch (latest) are explicit.

Proof of Work

Test TBD

Checklist

• Have you linked a jira ticket and/or is the ticket in the title?
• Have you checked whether your jira ticket required DOCSP changes?
• Have you signed our CLA?