Merge bitcoin/bitcoin#22153: test: Fix p2p_leak.py intermittent failure

ca3a77068b test: Fix p2p_leak.py intermittent failure by lowering timeout (Martin Zumsande)

Pull request description:

  Fixes #22085

  Root cause: There was just 1 second between the wait (5 seconds) and the `-peertimeout=4`.
  Since `ShouldRunInactivityChecks` in `net.cpp` measures the timeout in seconds, its result can only change once per second, even though it is called more often.
  So in situations when the connection is established early in a given second like [here](https://bitcoinbuilds.org/index.php?ansilog=d7b3e075-683a-45cc-94d4-9645fc17e0b6.log#l3117) (2021-05-27T12:28:04.**001**913Z ), the 1 second leeway was not be sufficient, leading to the intermittent failures.

  Fix this by lowering the timeout by one second.

ACKs for top commit:
  MarcoFalke:
    re-ACK ca3a77068b

Tree-SHA512: e7e22356d276c65a5b4f0a1b7ee5a9ad07d27691220746c7d02af3fad22cab1d53fd0ef59a938167ec80e4571c96649132d6922ad10667fc91baa47892f27a3e

test/functional/p2p_leak.py

@@ -29,6 +29,8 @@ from test_framework.util import (
     assert_greater_than_or_equal,
 )
 
+PEER_TIMEOUT = 3
+
 
 class LazyPeer(P2PInterface):
     def __init__(self):
@@ -98,7 +100,7 @@ class P2PVersionStore(P2PInterface):
 class P2PLeakTest(BitcoinTestFramework):
     def set_test_params(self):
         self.num_nodes = 1
-        self.extra_args = [['-peertimeout=4']]
+        self.extra_args = [[f"-peertimeout={PEER_TIMEOUT}"]]
 
     def create_old_version(self, nversion):
         old_version_msg = msg_version()
@@ -134,7 +136,7 @@ class P2PLeakTest(BitcoinTestFramework):
         self.nodes[0].generate(nblocks=1)
 
         # Give the node enough time to possibly leak out a message
-        time.sleep(5)
+        time.sleep(PEER_TIMEOUT + 2)
 
         # Make sure only expected messages came in
         assert not no_version_idle_peer.unexpected_msg