Un-quarantine instance level project template spec

What does this MR do?

Un-quarantine instance level project template spec

Closes gitlab-org/quality/staging#51 (closed)

This test has proven itself to be stable The flakiness was fixed in https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/10861

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• Separation of EE specific content