mgr/cephadm: make setting --cgroups=split configurable

mgr/cephadm: make setting --cgroups=split configurable

Previously, we were just always setting this as long
as users were using podman with a high enough version,
but it seems a user has run into an issue where their
daemons are failing to deploy with

Error: could not find cgroup mount in "/proc/self/cgroup"

despite having a podman with high enough version.

Fixes: https://tracker.ceph.com/issues/57096
Signed-off-by: Adam King <adking@redhat.com>