Move CNCF Kubernetes to new provider structure (#46436)

* Move CNCF Kubernetes to new provider structure

* Fix doc include path and k8s test

* Fix taskflow tutorial

* Fix test_project_structure

* Strip src. prefix instead of replacing all src.

Co-authored-by: Kalyan R <kalyan.ben10@live.com>

* Merge fix get_classes_from_file #46454

* Fix TestCncfProviderProjectStructure
- rename PROVIDER from "cncf" to "cncf/kubernetes"
- remove MISSING_EXAMPLES_FOR_CLASSES

* Fix k8s CI requirements

* fixup! Fix k8s CI requirements

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Co-authored-by: Kalyan R <kalyan.ben10@live.com>
Co-authored-by: Jarek Potiuk <jarek@potiuk.com>