Revert "PR#2944: decode protonmsg props field when loading from db"

This reverts commit 34d1c8eb9e, reversing
changes made to fdccd38148.

Proper solution was part of https://pagure.io/koji/pull-request/2955, so
this merge was a mistake. Reverting.

plugins/hub/protonmsg.py

@@ -350,11 +350,6 @@ def handle_db_msgs(urls, CONFIG):
                                aliases=('id', 'address', 'props', 'body'),
                                opts={'order': 'id', 'limit': limit})
         msgs = list(query.execute())
-        for msg in msgs:
-            try:
-                msg['props'] = json.loads(msg['props'])
-            except Exception:
-                LOG.error('Unable to load message from db: %r', msg)
         if not msgs:
             return
         if CONFIG.getboolean('broker', 'test_mode', fallback=False):