test_helpers: Remove unused timeout_mock.

We don’t want to encourage more uses of zerver.lib.timeout.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

zerver/lib/test_helpers.py

@@ -736,18 +736,6 @@ def mock_queue_publish(
         yield inner
 
 
-@contextmanager
-def timeout_mock(mock_path: str) -> Iterator[None]:
-    # timeout() doesn't work in test environment with database operations
-    # and they don't get committed - so we need to replace it with a mock
-    # that just calls the function.
-    def mock_timeout(seconds: int, func: Callable[[], object]) -> object:
-        return func()
-
-    with mock.patch(f"{mock_path}.timeout", new=mock_timeout):
-        yield
-
-
 @contextmanager
 def ratelimit_rule(
     range_seconds: int,