Enable `ci_build_tags_limit` feature flag by default
Description
In #338479 (closed) and !68380 (merged) we shipped a limit to how many tags a CI/CD build can have.
This got released on gitlab.com behind a ci_build_tags_limit
feature flag.
Proposal
Enable this feature flag by default and remove in a few releases from now.
/cc @morefice @jreporter