test/rgw/multisite: fix parsing of 'topic list' output

adjust the parsing to match changes from 3f0428a

Fixes: https://tracker.ceph.com/issues/70729

Signed-off-by: Casey Bodley <[email protected]>

Author: cbodley

src/test/rgw/rgw_multi/tests.py

@@ -548,8 +548,7 @@ def get_topics(zone):
     """
     cmd = ['topic', 'list'] + zone.zone_args()
     topics_json, _ = zone.cluster.admin(cmd, read_only=True)
-    topics = json.loads(topics_json)
-    return topics['topics']
+    return json.loads(topics_json)
 
 
 def create_topic_per_zone(zonegroup_conns, topics_per_zone=1):