We discussed the upgarde path testing in PTG[1] and agreed to
support two distro version when a release bumping to new version.
Let's document the existing and new testing recommendation for
upgrade in PTI.
Also change the 2023.1 tetsing runtime accordingly.
[1] https://etherpad.opendev.org/p/tc-2023-1-ptg#L422
Change-Id: I829ad6325f92c9162edf61046d3a46cb61e55a09
It updates the ubuntu version to 22.04 and python
version to py3.10 which is default in Ubuntu 22.04.
Python 3.9 and python3.10 will be the two versions
to test in 2023.1 cycle.
Moving Centos stream in the list of 'Best effort' to test
them.
Change-Id: I008d086279f0105561a74216a67a3aa9e624fec7