Reapply "test: p2p: check that connecting to ourself leads to disconnect"

This reverts commit 9ec2c53 with
a tiny change included (identation of the wait_until call).

Author: theStack

test/functional/p2p_handshake.py

@@ -17,6 +17,7 @@
     NODE_WITNESS,
 )
 from test_framework.p2p import P2PInterface
+from test_framework.util import p2p_port
 
 
 # Desirable service flags for outbound non-pruned and pruned peers. Note that
@@ -88,9 +89,11 @@ def run_test(self):
         with node.assert_debug_log([f"feeler connection completed"]):
             self.add_outbound_connection(node, "feeler", NODE_NONE, wait_for_disconnect=True)
 
-        # TODO: re-add test introduced in commit 5d2fb14bafe4e80c0a482d99e5ebde07c477f000
-        # ("test: p2p: check that connecting to ourself leads to disconnect") once
-        # the race condition causing issue #30368 is fixed
+        self.log.info("Check that connecting to ourself leads to immediate disconnect")
+        with node.assert_debug_log(["connected to self", "disconnecting"]):
+            node_listen_addr = f"127.0.0.1:{p2p_port(0)}"
+            node.addconnection(node_listen_addr, "outbound-full-relay", self.options.v2transport)
+            self.wait_until(lambda: len(node.getpeerinfo()) == 0)
 
 
 if __name__ == '__main__':