This is an alternative approach to commit
68bb43535e. I think this proposes a
better overall solution that the prior change which had the Python 3
packages being installed, but did not specify the _do_py3 flag to do
the installation steps that redirect the various tool installations.
Fedora 31+ doesn't have python2, and Tumbleweed does have some Python
2 support but there seems to be no reason to bother updating this
element for either with infra very close to removing this completely
[1]. Error out on these platforms, and add a release note.
The 15 path should include the python2 and python3 packages, along
with the flags to do the "cleanup"; i.e. forced removal of distutils
packages that pip 10+ won't touch. As mentioned in the original
change, the six package causes problems here, but we can clear that
too by explicitly listing it instead of letting it come in via
dependencies. Again, this element will be removed from the infra 15
builds ASAP; but we can release with this to provide a roll-back point
if we need to revert the removal to fix things temporarily.
Add it to the testing path as well.
[1] https://docs.opendev.org/opendev/infra-specs/latest/specs/cleanup-test-node-python.html
Change-Id: I7a6a342461d6001c25e55638ba9b7438c28f2519
