test: fix intermittent failure in wallet_reorgsrestore.py

Wait until the node's process has fully stopped before starting a new instance.

Since the same code is used in tool_wallet.py, this consolidates the behavior
into a 'kill_process()' function.

test/functional/test_framework/test_node.py

@@ -443,6 +443,11 @@ class TestNode():
             kwargs["expected_ret_code"] = 1 if expect_error else 0  # Whether node shutdown return EXIT_FAILURE or EXIT_SUCCESS
         self.wait_until(lambda: self.is_node_stopped(**kwargs), timeout=timeout)
 
+    def kill_process(self):
+        self.process.kill()
+        self.wait_until_stopped(expected_ret_code=1 if platform.system() == "Windows" else -9)
+        assert self.is_node_stopped()
+
     def replace_in_config(self, replacements):
         """
         Perform replacements in the configuration file.

test/functional/tool_wallet.py

@@ -5,7 +5,6 @@
 """Test bitcoin-wallet."""
 
 import os
-import platform
 import random
 import stat
 import string
@@ -536,9 +535,7 @@ class ToolWalletTest(BitcoinTestFramework):
         # Next cause a bunch of writes by filling the keypool
         wallet.keypoolrefill(wallet.getwalletinfo()["keypoolsize"] + 100)
         # Lastly kill bitcoind so that the LSNs don't get reset
-        self.nodes[0].process.kill()
-        self.nodes[0].wait_until_stopped(expected_ret_code=1 if platform.system() == "Windows" else -9)
-        assert self.nodes[0].is_node_stopped()
+        self.nodes[0].kill_process()
 
         wallet_dump = self.nodes[0].datadir_path / "unclean_lsn.dump"
         self.assert_raises_tool_error("LSNs are not reset, this database is not completely flushed. Please reopen then close the database with a version that has BDB support", "-wallet=unclean_lsn", f"-dumpfile={wallet_dump}", "dump")

test/functional/wallet_reorgsrestore.py

@@ -115,7 +115,7 @@ class ReorgsRestoreTest(BitcoinTestFramework):
         assert_equal(wallet.gettransaction(coinbase_tx_id)['details'][0]['abandoned'], True)
 
         # Abort process abruptly to mimic an unclean shutdown (no chain state flush to disk)
-        node.process.kill()
+        node.kill_process()
 
         # Restart the node and confirm that it has not persisted the last chain state changes to disk
         self.start_node(0)