Default enable FF validate-release-with-author

What does this MR do and why?

Default enable FF #365350 (closed) as we have validated it to work fine in production for a week.

Links that were Monitored for validation:

• https://log.gprd.gitlab.net/goto/ff353bd0-8ced-11ed-85ed-e7557b0a598c
• https://log.gprd.gitlab.net/goto/2fb883c0-8cee-11ed-9f43-e3784d7fe3ca
• https://sentry.gitlab.net/gitlab/gitlabcom/?query=is%3Aunresolved+%2Fapi%2F%2A%2Fprojects%2F%2A%2Freleases

Also ensured today(11 Jan 2022) that there were no empty releases without author_id on gitlab.com.

[ gprd ] production> Release.where(:author_id => nil).count
=> 0

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #365350 (closed)