Merge bitcoin#31837: test: add missing sync to p2p_tx_download.py

8fe552f test: add missing sync to p2p_tx_download.py (Martin Zumsande)

Pull request description:

  If the node hasn't processed the inv from the outbound peer before the mocktime bump, the peer won't be preferred after the other inv timeouts, failing the test . Therefore, add a sync, just  like there is one after the `send_message` calls in the previous lines.

  Fixes bitcoin#31833

ACKs for top commit:
  maflcko:
    lgtm ACK 8fe552f
  instagibbs:
    ACK 8fe552f

Tree-SHA512: fda935d8a4081b5ecae96f5a73c04f4bb91feaeb09b5c159ffd45cf16668c4345ff268c57f383ba7c7ff544ee07b21f97aa28f257ade809c18b9310837795e7a

test/functional/p2p_tx_download.py

@@ -274,6 +274,7 @@ def test_preferred_tiebreaker_inv(self):
         pref_peer = self.nodes[0].add_outbound_p2p_connection(
            TestP2PConn(), wait_for_verack=True, p2p_idx=1, connection_type="outbound-full-relay")
         pref_peer.send_message(msg_inv([CInv(t=MSG_WTX, h=0xff00ff00)]))
+        pref_peer.sync_with_ping()
 
         assert_equal(len(self.nodes[0].getpeerinfo()), NUM_INBOUND + 2)