qa/cephfs: run() cleanup whether FS was mounted or not

qa/cephfs: run() cleanup whether FS was mounted or not

In case the mount command in mount() fails, it would still have created
the mountpoint and network namespace for the FS's mount. Therefore, run
cleanup() and cleanup_netns() in umount() and umount_wait() even when
self.mounted is set to False.

Also, move the call to cleanup_netns() in cleanup().

Fixes: https://tracker.ceph.com/issues/45430
Signed-off-by: Rishabh Dave <ridave@redhat.com>