Update KubeResourceManager api for kubernetes clients

[kornys]

Description

1. Remove static ability to get clients because clients are not initialized without singleton is initialized first so it is save to get it from instance.
2. remove the get.. prefix from kubeClient() and kubeCmdClient()

Type of Change

Please delete options that are not relevant.

• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit/integration tests pass locally with my changes