Background and Approach (Required)

• Now that the Keycloak removal PR has merged, we can modify the documentation to remove keycloak references except for those that relate to migrate to self-managed solution.

Acceptance Criteria (Mandatory)

• Add OpenShift GitOps doc notice indicating the field is removed.
• Remove 'Configuring SSO for Argo CD for Keycloak' doc topic
• Ensure that remaining documentation provides enough information for users to know how to migrate.