Now that 7.10 is out if we review the state of play....

the effective use of 7.x becomes 7.12.x
and the 7.11.x branch can be created.
and we can retire 7.9.x as it will have no more back-ports, I don't think. we should check w team leads to be sure on that tho, lol

Manu notes we need to impact these decisions and review into a few places:

• the backport.json file
• the actual branches (creation)
• the ci execution in Jenkins
• anything else we're forgetting?!