Merge bitcoin/bitcoin#23532: test: add functional test for -startupnotify

126853214a test: add functional test for -startupnotify (Bruno Garcia)

Pull request description:

  This PR adds a functional test for -startupnotify. It basically starts the node passing a command on -startupnotify to create a file on tmp and then, we check if the file has been successfully created.

ACKs for top commit:
  theStack:
    Tested ACK 126853214a
  kristapsk:
    re-ACK 126853214a

Tree-SHA512: 5bf3e46124ee5c9d609c9993e6465d5a71a8d2275dcf07c8ce0549f013f7f8863d483b46b7164152f566468a689371ccb87f01cf118c3c9cac5b2be673b61a5c

test/functional/test_runner.py

@@ -257,6 +257,7 @@ BASE_SCRIPTS = [
     'wallet_bumpfee.py --descriptors',
     'wallet_implicitsegwit.py --legacy-wallet',
     'rpc_named_arguments.py',
+    'feature_startupnotify.py',
     'wallet_listsinceblock.py --legacy-wallet',
     'wallet_listsinceblock.py --descriptors',
     'wallet_listdescriptors.py --descriptors',