Remove required fields from OpenAPI schema that don’t exist

[plarson]

What kind of change does this PR introduce?

Bug fix - Corrects the OpenAPI schema definition by removing invalid required field specifications.

What is the current behavior?

I used swagger2openapi to generate an OpenAPI yml from the swagger endpoint. The OpenAPI schema in lib/supavisor_web/open_api_schemas.ex incorrectly lists some fields as required that don't actually exist in the schema definition, which makes client side OpenAPI validation fail.

What is the new behavior?

The schema's required fields list has been updated to only include fields that actually exist in the schema definition.