[refactor] use waiting inside disconnect_p2ps

-Use wait_for_disconnect instead of manual
wait after calling disconnect_p2ps.

test/functional/p2p_leak.py

@@ -132,9 +132,6 @@ class P2PLeakTest(BitcoinTestFramework):
 
         self.nodes[0].disconnect_p2ps()
 
-        # Wait until all connections are closed
-        wait_until(lambda: len(self.nodes[0].getpeerinfo()) == 0)
-
         # Make sure no unexpected messages came in
         assert no_version_bannode.unexpected_msg == False
         assert no_version_idlenode.unexpected_msg == False

test/functional/p2p_node_network_limited.py

@@ -83,7 +83,6 @@ class NodeNetworkLimitedTest(BitcoinTestFramework):
         assert_equal(node1.firstAddrnServices, expected_services)
 
         self.nodes[0].disconnect_p2ps()
-        node1.wait_for_disconnect()
 
         # connect unsynced node 2 with pruned NODE_NETWORK_LIMITED peer
         # because node 2 is in IBD and node 0 is a NODE_NETWORK_LIMITED peer, sync must not be possible