Improve performance of project snippet controller spec

What does this MR do?

In this MR we improve the performance of spec/controllers/projects/snippets_controller_spec.rb.

In local, the time before the changes is 1 min and 24 seconds. The current time is 51 seconds. Therefore, the improvement is 33 seconds.

Queries saved: 4245

Does this MR meet the acceptance criteria?

Conformity

• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Closes #228693 (closed)