qa: Add mgr snapshot mirror status tests

qa: Add mgr snapshot mirror status tests

Add teuthology coverage for `ceph fs snapshot mirror status`:
parity with asok peer_status, default idle metrics, stale omap
handling, error paths, filter scopes, daemon restart, and cache TTL.

Reuse existing peer_dir_status and metrics assertion helpers.
Adjust stale test wait for InstanceWatcher timeout and set a
short cache TTL in the cache test. Pass peer_uuid via --peer_uuid=
in the test helper for peer-only scope queries.

Fixes: https://tracker.ceph.com/issues/76686
Signed-off-by: Kotresh HR <khiremat@redhat.com>