* Reduce redundancy in python docs
This is a followup to PR #5094, which had a few unresolved comments at
merge time. This reduces the amount of redundant lines in the api
example doc templates, and ensures that referenced Configuration objects
are actually instantiated.
* Regenerate samples
* [python] Cleanup ThreadPool with atexit rather than __del__
This removes the `__del__` function from the generated Python client,
and replaces it with a `cleanup` function. When a ThreadPool is created,
the cleanup function is registered with the `atexit` module.
This fixes#5093, where the API client could hang indefinitely at
garbage collection.
* Update petstore examples
* Test to ensure threadpool is cleaned up
* Docs now encourage using the context manager
* Regenerate docs
* Update samples
