Rails5 fix commit statuses spec

What does this MR do?

Disable Sidekiq inline testing in order not to hit the query limit. This was happening for Rails 5.

The extra sql queries are 5 extra SAVEPOINT active_record_1 and RELEASE SAVEPOINT active_record_1 pairs. However, the query logs of Rails 4 from development have these same transactions for this endpoint. I compared the query logs of the specs of Rails 5 with the logs of this endpoint in Rails 4(with sidekiq inline enabled) and they had the same commit(or savepoint in specs) queries.

Since this is an inconsistency in Rails 4 testing, I decided just to turn off sidekiq inline testing to prevent the requests from hitting the query limit as the queries from inline sidekiq workers are counted in the query limiting check.

What are the relevant issue numbers?

Closes #7087 (closed)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• Tests added for this feature/bug
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• EE specific content should be in the top level /ee folder
• For a paid feature, have we considered GitLab.com plans, how it works for groups, and is there a design for promoting it to users who aren't on the correct plan?