Merge #20176: test: Fix intermittent issue in p2p_feefilter

fa5a91a test: Fix typo (one tx is enough) in p2p_feefilter (MarcoFalke)
fa3af2c test: Fix intermittent issue in p2p_feefilter (MarcoFalke)

Pull request description:

  Fixes:

  ```
  Traceback (most recent call last):
    File "test/functional/test_framework/test_framework.py", line 126, in main
      self.run_test()
    File "test/functional/p2p_feefilter.py", line 63, in run_test
      self.test_feefilter()
    File "test/functional/p2p_feefilter.py", line 117, in test_feefilter
      txids = [miniwallet.send_self_transfer(fee_rate=Decimal('0.00020000'), from_node=node1)['wtxid'] for _ in range(3)]
    File "test/functional/p2p_feefilter.py", line 117, in <listcomp>
      txids = [miniwallet.send_self_transfer(fee_rate=Decimal('0.00020000'), from_node=node1)['wtxid'] for _ in range(3)]
    File "test/functional/test_framework/wallet.py", line 63, in send_self_transfer
      txid = from_node.sendrawtransaction(tx_hex)
    File "test/functional/test_framework/coverage.py", line 47, in __call__
      return_val = self.auth_service_proxy_instance.__call__(*args, **kwargs)
    File "test/functional/test_framework/authproxy.py", line 146, in __call__
      raise JSONRPCException(response['error'], status)
  test_framework.authproxy.JSONRPCException: bad-txns-inputs-missingorspent (-25)

ACKs for top commit:
  guggero:
    ACK fa5a91a

Tree-SHA512: 51d885753f72e1c91c4580709c15bdab60ff8c9d6f9bcb6db78a560e7e4dd7f76ce23add3303b374174afa3f11f74aa61db189a90c68d7f7655b15e64f51ed96

test/functional/p2p_feefilter.py

@@ -108,9 +108,10 @@ def test_feefilter(self):
         # to 35 entries in an inv, which means that when this next transaction
         # is eligible for relay, the prior transactions from node1 are eligible
         # as well.
-        txids = [miniwallet.send_self_transfer(fee_rate=Decimal('0.00020000'), from_node=node0)['wtxid'] for _ in range(3)]
+        txids = [miniwallet.send_self_transfer(fee_rate=Decimal('0.00020000'), from_node=node0)['wtxid'] for _ in range(1)]
         conn.wait_for_invs_to_match(txids)
         conn.clear_invs()
+        self.sync_mempools()  # must be sure node 1 has received all txs
 
         self.log.info("Remove fee filter and check txs are received again")
         conn.send_and_ping(msg_feefilter(0))