ci: [NGOv2.X] Corrections of CI setup issues

[michalChrobot]

This PR focuses on fixing simplifying CI setup by removing some unnecessary complexity and adding comments to describe CI steps

1. UTR command was corrected to use preinstalled UTR on the image instead of downloading it
2. Removed upm-ci package pack definition and converted Code Coverage test to use upm-pvp pack job
3. Simplifies some unnecessary CI commands
4. Added detailed comments regarding CI setup and commands
5. Created CI_README file which describes overall configuration structure.
6. For macOS devices we now use M1 model (Apple Silicon) in contrast to default x64 Intel Mac which introduced a lot of bit-flipping errors

[EmandM]

Same comment here, Github treats README.md files special, so it's best to simply use README.md