Move to CODEOWNERS generated OWNERS files

[stp-ip]

Is this a BUG REPORT or FEATURE REQUEST?:
feature

What happened:
Currently we use OWNER files inspired by Kubernetes et al.

What you expected to happen:
Use CODEOWNERS supported by Github.

Anything else we need to know?:
https://help.github.com/en/github/creating-cloning-and-archiving-repositories/about-code-owners