Merge #20613: test: Use Popen.wait instead of RPC in assert_start_raises_init_error

fa918dd test: Use Popen.wait instead of RPC in assert_start_raises_init_error (MarcoFalke)

Pull request description:

  Using RPC (`wait_for_rpc_connection`) has several issue:

  * It polls in a loop, which might be slow
  * It tries to read the RPC cookie file, which might not be present, thus leading to intermittent issues

  Fix both by using `Popen.wait`

ACKs for top commit:
  laanwj:
    Code review ACK ~~faf7b05be9c86ee61c39e5314511fe2410128a6b~~ fa918dd
  darosior:
    ACK fa918dd

Tree-SHA512: 5368ad0d0ea2deb0af9582a42667c9290efe8f2705f37a236afc2c7908b04265ab342e2dd356a57156e99389f4a27ab6da9fa7bf9161fb7568240aa005e693b9

Author: MarcoFalke

test/functional/test_framework/test_node.py

@@ -482,11 +482,8 @@ def assert_start_raises_init_error(self, extra_args=None, expected_msg=None, mat
              tempfile.NamedTemporaryFile(dir=self.stdout_dir, delete=False) as log_stdout:
             try:
                 self.start(extra_args, stdout=log_stdout, stderr=log_stderr, *args, **kwargs)
-                self.wait_for_rpc_connection()
-                self.stop_node()
-                self.wait_until_stopped()
-            except FailedToStartError as e:
-                self.log.debug('bitcoind failed to start: %s', e)
+                ret = self.process.wait(timeout=self.rpc_timeout)
+                self.log.debug(self._node_msg(f'bitcoind exited with status {ret} during initialization'))
                 self.running = False
                 self.process = None
                 # Check stderr for expected message
@@ -505,11 +502,15 @@ def assert_start_raises_init_error(self, extra_args=None, expected_msg=None, mat
                         if expected_msg != stderr:
                             self._raise_assertion_error(
                                 'Expected message "{}" does not fully match stderr:\n"{}"'.format(expected_msg, stderr))
-            else:
+            except subprocess.TimeoutExpired:
+                self.process.kill()
+                self.running = False
+                self.process = None
+                assert_msg = f'bitcoind should have exited within {self.rpc_timeout}s '
                 if expected_msg is None:
-                    assert_msg = "bitcoind should have exited with an error"
+                    assert_msg += "with an error"
                 else:
-                    assert_msg = "bitcoind should have exited with expected error " + expected_msg
+                    assert_msg += "with expected error " + expected_msg
                 self._raise_assertion_error(assert_msg)
 
     def add_p2p_connection(self, p2p_conn, *, wait_for_verack=True, **kwargs):