test/rgw: SystemObject.json_command no longer trims json output

this was a workaround for 'period commit' commands that used to write
the "Sending period to new master zone" line to stdout

Signed-off-by: Casey Bodley <cbodley@redhat.com>

src/test/rgw/rgw_multi/multisite.py

@@ -72,8 +72,7 @@ class SystemObject:
         data and retcode """
         s, r = self.command(cluster, cmd, args or [], **kwargs)
         if r == 0:
-            output = s[s.find('{'):] # trim extra output before json
-            data = json.loads(output)
+            data = json.loads(s)
             self.load_from_json(data)
             self.data = data
         return self.data, r