VOLTHA Release: Create all VOLTHA bugfix branches at release time

VOLTHA TST Meeting Task Item:

• Update release process to create bugfix branches at release time rather than lazy-branching on demand.
• Initial pass branches can be created manually (voltha-{ver}) as needed.
• Long term a script should be setup to validate repository state and create a voltha-{ver} branch.

 https://docs.google.com/document/d/1mNqronCip_-tDjFI-ZoudNteC3AnOcVONPHz7HuW8Eg/edit#heading=h.vo7sg94myqiv

• VOL-4775 - Create bugfix branch voltha-2.10 for VOL-4774
• Branch created, need to verify usable with Holger.
• Also related edits in the docs.voltha.org Release page are on the way.
• DONE - Verified by holger
• TODO - Transition from lazy branching to full branch post release.
• Docs.voltha.org will need to be updated.
• Update branching and tagging scripts or create a set of them to automate bugfix branch creation if needed.