Merge bitcoin/bitcoin#30468: test: bump mocktime only after node has received and sent bytes

c322bdd test: bump mocktime after node has received and sent bytes (stratospher)

Pull request description:

  Fixes an intermittent failure for `p2p_v2_misbehaving.py` reported in bitcoin/bitcoin#30420 (comment).

  A [different error message](https://github.com/bitcoin/bitcoin/blob/262260ce1e919613ba60194a5861b0b0a51dfe01/src/net.cpp#L1970) `"socket no message in first %i seconds"` will be displayed if `m_last_send=0` or if `m_last_recv is 0`.  Fix this by:
  1. mocktime bump is done after all the bytes are received. (`m_last_recv is not 0 now`)
  2. wait until bytes are sent by `TestNode`/`bitcoind` (`m_last_send is not 0 now`)

  See https://cirrus-ci.com/task/5359619151757312?logs=ci#L3935 for an example failure (I wasn't able to reproduce the intermittent failure locally but I think the fix is logical)

ACKs for top commit:
  maflcko:
    reACK c322bdd

Tree-SHA512: 1c05524c2819041eb2001c2baf2c912d4f812a39347f784f212634e8c53131357a73116a46b4b7542bc7fc8c1370c4d36fc9898a2cbdb40bcee61105123c4a35

Author: fanquake

test/functional/p2p_v2_misbehaving.py

@@ -147,11 +147,11 @@ def test_earlykeyresponse(self):
         peer1.v2_state.can_data_be_received = True
         self.wait_until(lambda: peer1.v2_state.ellswift_ours)
         peer1.send_raw_message(peer1.v2_state.ellswift_ours[4:] + peer1.v2_state.sent_garbage)
-        node0.bumpmocktime(3)
         # Ensure that the bytes sent after 4 bytes network magic are actually received.
         self.wait_until(lambda: node0.getpeerinfo()[-1]["bytesrecv"] > 4)
+        self.wait_until(lambda: node0.getpeerinfo()[-1]["bytessent"] > 0)
         with node0.assert_debug_log(['V2 handshake timeout peer=0']):
-            node0.bumpmocktime(1)  # `InactivityCheck()` triggers now
+            node0.bumpmocktime(4)  # `InactivityCheck()` triggers now
             peer1.wait_for_disconnect(timeout=1)
         self.log.info('successful disconnection since modified ellswift was sent as response')