Merge #18895: p2p: unbroadcast followups: rpcs, nLastResend, mempool sanity check

651f1d816f [test] wait for inital broadcast before comparing mempool entries (gzhao408)
9d3f7eb986 [mempool] sanity check that all unbroadcast txns are in mempool (gzhao408)
a7ebe48b94 [rpc] add unbroadcast info to mempool entries and getmempoolinfo (gzhao408)
d160069604 [wallet] remove nLastResend logic (gzhao408)

Pull request description:

  Followup to #18038 by amitiuttarwar which introduces the unbroadcast set: "a mechanism for the mempool to track locally submitted transactions" and decreases the frequency of rebroadcast from 10-15 minutes to 12-36 hours.

  This PR addresses some of the outstanding TODOs building on top of it:
  - remove `nLastResend` logic, which is used to ensure rebroadcast doesn't happen again if no new block has been mined (makes sense in 10-15 min period, but not necessary for 12-36 hour period). (#18038 [comment](https://github.com/bitcoin/bitcoin/pull/18038#discussion_r416826914))
  - expose unbroadcast info via RPCs, for more informative queries and testing (#18038 [comment](https://github.com/bitcoin/bitcoin/pull/18038#discussion_r416837980))
  - add sanity check to verify unbroadcast transactions still exist in mempool before rebroadcasting (#18038 [comment](https://github.com/bitcoin/bitcoin/pull/18038#discussion_r416861609))

ACKs for top commit:
  naumenkogs:
    Code review ACK 651f1d816f
  amitiuttarwar:
    ACK 651f1d816f 🎉
  MarcoFalke:
    Review ACK 651f1d816f

Tree-SHA512: d5327e95ef39d44152b48df5c610502ae11c168f43dbbfb2885340c93d1ba9426eb3a5794573f5fc843502109cb3ffb63efa3f2db4f8f112efcde8f76d9a8845

test/functional/test_framework/mininode.py

@@ -645,6 +645,7 @@ class P2PTxInvStore(P2PInterface):
         self.tx_invs_received = defaultdict(int)
 
     def on_inv(self, message):
+        super().on_inv(message) # Send getdata in response.
         # Store how many times invs have been received for each tx.
         for i in message.inv:
             if i.type == MSG_TX:
@@ -654,3 +655,12 @@ class P2PTxInvStore(P2PInterface):
     def get_invs(self):
         with mininode_lock:
             return list(self.tx_invs_received.keys())
+
+    def wait_for_broadcast(self, txns, timeout=60):
+        """Waits for the txns (list of txids) to complete initial broadcast.
+        The mempool should mark unbroadcast=False for these transactions.
+        """
+        # Wait until invs have been received (and getdatas sent) for each txid.
+        self.wait_until(lambda: set(self.get_invs()) == set([int(tx, 16) for tx in txns]), timeout)
+        # Flush messages and wait for the getdatas to be processed
+        self.sync_with_ping()