enhance: allow uses to disable broker heartbeats by not providing a timeout

kombu/mixins.py

@@ -195,9 +195,10 @@ class ConsumerMixin:
                 try:
                     conn.drain_events(timeout=safety_interval)
                 except socket.timeout:
+                    if timeout:
                         conn.heartbeat_check()
                         elapsed += safety_interval
-                    if timeout and elapsed >= timeout:
+                        if elapsed >= timeout:
                             raise
                 except OSError:
                     if not self.should_stop: