Follow-up from "Add query for AI CI chat messages"

The following discussion from !120181 (merged) should be addressed:

• @dstull started a discussion: (+2 comments)

  question (non-blocking):

  Why do we disable this here/not define an owner?

The two spec files:

• ee/spec/graphql/types/ai/message_type_spec.rb
• ee/spec/models/ai/project/conversations_spec.rb

have feature_category: :not_owned, but they could be shared which is probably a better description of the responsibility over them.