Remove Python versions of OIDC/Pulumi Cloud

[jkodroff]

trafficstars

• The Python versions don't have the right audience claim.
• The TS versions do, and we don't gain much from maintaining the codebase in multiple languages.
• Add CODEOWNERS with ownership for AWS and GCP OIDC setup.

[jkodroff]

Need to check whether there are links to this codebase from the docs.