Removed omniauth provider causing invalid application setting

Summary

At some point, OmniAuth was disabled and the provider configuration was removed. However, when trying to save application settings, we see a form error Disabled oauth sign in sources 'github' is not an OAuth sign-in source.

Relevant logs and/or screenshots

Version 10.7.3-ee

Customer ticket -> https://gitlab.zendesk.com/agent/tickets/96539 (internal)