Fix spam in issue creation by making project private

What does this MR do?

Fixes spam in issue creation by making project private

CE port: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/30997

Closes gitlab-org/quality/staging#63 (closed)

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