cephadm: convert calls to get_container_{mounts,binds} to method calls

cephadm: convert calls to get_container_{mounts,binds} to method calls

In get_container, convert calls to get_container_binds and
get_container_mounts to direct uses of the ContainerDaemonForm customize
methods, avoiding constructing said ContainerDaemonForm subclasses
redundantly.
This is all done in one pass because the _update_podman_mounts function
is called by get_container_mounts and trying to convert each type at a
time would result in extra calls to that function.

Signed-off-by: John Mulligan <jmulligan@redhat.com>