qa: add test for mgr status command

Fixes: https://tracker.ceph.com/issues/70571
Signed-off-by: Patrick Donnelly <[email protected]>

Author: batrick

qa/suites/rados/mgr/tasks/3-mgrmodules.yaml

@@ -6,3 +6,6 @@ mgrmodules:
 tasks:
   - sequential:
       - mgrmodules
+      - exec:
+          mon.a:
+            - ceph tell mgr status