Merge #18982: wallet: Minimal fix to restore conflicted transaction notifications

7eaf86d3bf trivial: Suggested cleanups to surrounding code (Russell Yanofsky)
b604c5c8b5 wallet: Minimal fix to restore conflicted transaction notifications (Russell Yanofsky)

Pull request description:

  This fix is a based on the fix by Antoine Riard (ariard) in https://github.com/bitcoin/bitcoin/pull/18600.

  Unlike that PR, which implements some new behavior, this just restores previous wallet notification and status behavior for transactions removed from the mempool because they conflict with transactions in a block. The behavior was accidentally changed in two `CWallet::BlockConnected` updates: a31be09bfd and 7e89994133 from https://github.com/bitcoin/bitcoin/pull/16624, causing issue https://github.com/bitcoin/bitcoin/issues/18325.

  The change here could be improved and replaced with a more comprehensive cleanup, so it includes a detailed comment explaining future considerations.

  Fixes #18325

  Co-authored-by: Antoine Riard (ariard)

ACKs for top commit:
  jonatack:
    Re-ACK 7eaf86d3bf
  ariard:
    ACK 7eaf86d, reviewed, built and ran tests.
  MarcoFalke:
    ACK 7eaf86d3bf 🍡

Tree-SHA512: 9a1efe975969bb522a9dd73c41064a9348887cb67883cd92c6571fd2df4321b9f4568363891abdaae14a3b9b168ef8142e95c373fc04677e46289b251fb84689

test/functional/feature_notifications.py

@@ -125,12 +125,7 @@ class NotificationsTest(BitcoinTestFramework):
 
             # Bump tx2 as bump2 and generate a block on node 0 while
             # disconnected, then reconnect and check for notifications on node 1
-            # about newly confirmed bump2 and newly conflicted tx2. Currently
-            # only the bump2 notification is sent. Ideally, notifications would
-            # be sent both for bump2 and tx2, which was the previous behavior
-            # before being broken by an accidental change in PR
-            # https://github.com/bitcoin/bitcoin/pull/16624. The bug is reported
-            # in issue https://github.com/bitcoin/bitcoin/issues/18325.
+            # about newly confirmed bump2 and newly conflicted tx2.
             disconnect_nodes(self.nodes[0], 1)
             bump2 = self.nodes[0].bumpfee(tx2)["txid"]
             self.nodes[0].generatetoaddress(1, ADDRESS_BCRT1_UNSPENDABLE)
@@ -138,7 +133,7 @@ class NotificationsTest(BitcoinTestFramework):
             assert_equal(tx2 in self.nodes[1].getrawmempool(), True)
             connect_nodes(self.nodes[0], 1)
             self.sync_blocks()
-            self.expect_wallet_notify([bump2])
+            self.expect_wallet_notify([bump2, tx2])
             assert_equal(self.nodes[1].gettransaction(bump2)["confirmations"], 1)
 
         # TODO: add test for `-alertnotify` large fork notifications