qa/suites/rados/thrash-old-clients: update supported releases and distro

qa/suites/rados/thrash-old-clients: update supported releases and distro

thrash-old-clients tests should only support N-3 releases. To fix this for
main, I have removed all releases < quincy and have added squid.

Also, we are fully switching to centos.9_stream packages/containers after
the centos.8_stream end of life, so I changed the distro from centos.8_stream
to centos.9_stream.

*** Note: If this commit is backported, it should be done in such a way that
only releases >= quincy reference centos.9_stream. For instance, if backporting to squid,
a reef/squid thrash test is okay to make references to centos.9_stream since both reef and
squid support this, but a pacific/squid test will have to take a different approach
since pacific does not support centos.9_stream.

Fixes: https://tracker.ceph.com/issues/66398
Signed-off-by: Laura Flores <lflores@ibm.com>
(cherry picked from commit 820e4004f3fd17a5daee955f7a1443b1501caaad)

Modifications:
- For this squid backport, I kept pacific since that fits into N-3 where
  N is squid.
- Pacific does not build c9 packages, so I picked an alternative distro
  that is shared among all represented releases: ubuntu 20.04.