qa/suites/rados/cephadm/upgrade: change starting version by distro
centos/rhel have podman 2, which does not like conflicting --cap-add and
--privileged arguments. cephadm versions prior to 15.2.5 use both args,
however, which means the rhel/centos upgrade test has to start at 15.2.5
to work at all on those distros (with the updated podman).
Fixes: https://tracker.ceph.com/issues/48142
Signed-off-by: Sage Weil <sage@newdream.net>
(cherry picked from commit
38e14f923508efc4a18e942869065771598ef915)