Enable FF_ENABLE_PLACEHOLDERS by default (!807) · Merge requests · GitLab.org / gitlab-pages

What does this MR do?

Enables the FF_ENABLE_PLACEHOLDERS feature flag by default.

I added the Changelog trailer (e.g. Changelog: added) to the commits that need to be included in the changelog
I added unit tests or they are not required
I added acceptance tests or they are not required
I added documentation (or it's not required)
I followed code review guidelines
I followed Go Style guidelines