partial Merge bitcoin#18878: test: Add test for conflicted wallet tx notifications

Backport notice:
we don't have bumpfee feature, so, only some part of code is backported

f963a68 test: Add test for conflicted wallet tx notifications (Russell Yanofsky)

Pull request description:

  Add test coverage for conflicted wallet transaction notifications so we can improve current behavior and avoid future regressions

  bitcoin#9240 - accidental break
  bitcoin#9479 - bug report
  bitcoin#9371 - fix
  bitcoin#16624 - accidental break
  bitcoin#18325 - bug report
  bitcoin#18600 - potential fix

ACKs for top commit:
  laanwj:
    ACK f963a68
  jonatack:
    re-ACK f963a68
  MarcoFalke:
    ACK f963a68

Tree-SHA512: d3a7952a2d3dc2ff0800ef857575ea4ef9759c0917d58a7fc91e2db0ca3cc3baf0dd0cf9af61683f691e5fefb11afe8120bb5810c7037ed9ecedee385dd4aa07

fixup dashify of feature_notifications

Author: laanwj

test/functional/feature_notifications.py

@@ -7,6 +7,7 @@
 import os
 
 from test_framework.address import ADDRESS_BCRT1_UNSPENDABLE
+
 from test_framework.test_framework import DashTestFramework
 from test_framework.util import (
     assert_equal,
@@ -95,6 +96,9 @@ def run_test(self):
             # directory content should equal the generated transaction hashes
             txids_rpc = list(map(lambda t: notify_outputname(self.wallet, t['txid']), self.nodes[1].listtransactions("*", block_count)))
             assert_equal(sorted(txids_rpc), sorted(os.listdir(self.walletnotify_dir)))
+            for tx_file in os.listdir(self.walletnotify_dir):
+                os.remove(os.path.join(self.walletnotify_dir, tx_file))
+
 
         self.log.info("test -chainlocknotify")
 
@@ -141,5 +145,6 @@ def run_test(self):
 
         # TODO: add test for `-alertnotify` large fork notifications
 
+
 if __name__ == '__main__':
     NotificationsTest().main()