[Koji] filter out prod builds by releng

We do not want to create updates for these.

packit_service_fedmsg/callbacks.py

@@ -54,6 +54,12 @@ def _koji(topic: str, event: dict, packit_user: str) -> CallbackResult:
                 pass_to_service=False,
             )
 
+        if event.get("owner") == "releng":
+            return CallbackResult(
+                msg="[Koji] Koji build built by 'releng'.",
+                pass_to_service=False,
+            )
+
         what = (
             f"[Koji] build:{event.get('build_id')} task:{event.get('task_id')}"
             f" {event.get('old')}->{event.get('new')}"