AttributeError: 'DefaultApiStub' object has no attribute 'CancelApiCalls'

## Expected Behavior

Upgrading from Python2 to Python3, I expected the following piece of code to continue working with this library.

```
try:
from google.appengine.api import runtime, apiproxy_stub_map

def hook():
logging.info("Instance is shutting down; cleaning up.")

apiproxy_stub_map.apiproxy.CancelApiCalls()

runtime.set_shutdown_hook(hook)
except ImportError:
pass
```

Is this deprecated? If yes, then should it be replaced with something else or is this functionality not needed any more? I can see the method somewhere in the library source code, but AppEngine seems not recognizing it?

## Actual Behavior

```
Traceback (most recent call last):
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/google/appengine/runtime/middlewares.py", line 140, in ErrorLoggingMiddleware
return app(wsgi_env, start_response)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/google/appengine/runtime/middlewares.py", line 82, in
lambda app: lambda wsgi_env, start_resp: f(app, wsgi_env, start_resp),
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/google/appengine/runtime/middlewares.py", line 375, in BackgroundAndShutdownMiddleware
runtime.__BeginShutdown()
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/google/appengine/api/runtime/runtime.py", line 122, in __BeginShutdown
shutdown_hook()
File "/workspace/components/campaigns/push/processor/apns/send.py", line 40, in hook
apiproxy_stub_map.apiproxy.CancelApiCalls()
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/google/appengine/api/apiproxy_stub_map.py", line 375, in CancelApiCalls
self.__default_stub.CancelApiCalls()
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'DefaultApiStub' object has no attribute 'CancelApiCalls'
```

## Steps to Reproduce the Problem

1. Install the shutdown hook
```
try:
from google.appengine.api import runtime, apiproxy_stub_map

def hook():
logging.info("Instance is shutting down; cleaning up.")

apiproxy_stub_map.apiproxy.CancelApiCalls()

runtime.set_shutdown_hook(hook)
except ImportError:
pass
```

2. Use the app engine service and wait for it to stop.

## Specifications

- Version: 1.1.6
- Platform: Google Appengine
- Python3.12