test: fix intermittent failure in p2p_orphan_handling.py

If we bump the mocktime before the node has successfully disconnected
the peer, the requests for both parents could be spread over
two GETDATAS, which would make the test fail.

Author: mzumsande

test/functional/p2p_orphan_handling.py

@@ -788,6 +788,7 @@ def test_parents_change(self):
 
         # Disconnect peer1. peer2 should become the new candidate for orphan resolution.
         peer1.peer_disconnect()
+        self.wait_until(lambda: node.num_test_p2p_connections() == 1)
         node.bumpmocktime(TXREQUEST_TIME_SKIP)
         self.wait_until(lambda: len(node.getorphantxs(verbosity=2)[0]["from"]) == 1)
         # Both parents should be requested, now that they are both missing.