External cloud providers should not rely on feature gates

Background

Code in library-go currently uses feature gates to determine if Azure and GCP clusters should be external or not. They have been promoted for at least one release and we do not see ourselves going back.

In 4.17 the code is expected to be deleted completely.

We should remove the reliance on the feature gate from this part of the code and clean up references to feature gate access at the call sites.

Steps

• Update library go to remove reliance on feature gates
• Update callers to no longer rely on feature gate accessor (KCMO, KASO, MCO, CCMO)
• Remove feature gates from API repo

Stakeholders

• Cluster Infra
• MCO team
• Workloads team
• API server team

Definition of Done

• Feature gates for external cloud providers are removed from the product

• Docs

• <Add docs requirements for this card>

• Testing

• <Explain testing that will be added>