(refactor router.py ) - PR 3 - Ensure all functions under 100 lines (#6181)

* add flake 8 check

* split up litellm _acompletion

* fix get model client

* refactor use commong func to add metadata to kwargs

* use common func to get timeout

* re-use helper to _get_async_model_client

* use _handle_mock_testing_rate_limit_error

* fix docstring for _handle_mock_testing_rate_limit_error

* fix function_with_retries

* use helper for mock testing fallbacks

* router - use 1 func for simple_shuffle

* add doc string for simple_shuffle

* use 1 function for filtering cooldown deployments

* fix use common helper to _get_fallback_model_group_from_fallbacks

.pre-commit-config.yaml

@@ -25,6 +25,11 @@ repos:
        exclude: ^litellm/tests/|^litellm/proxy/tests/
        additional_dependencies: [flake8-print]
        files: litellm/.*\.py
+    # -  id: flake8
+    #    name: flake8 (router.py function length)
+    #    files: ^litellm/router\.py$
+    #    args: [--max-function-length=40]
+    # #    additional_dependencies: [flake8-functions]
 -   repo: https://github.com/python-poetry/poetry
     rev: 1.8.0
     hooks: