Merge branch '419808-enable-git-blame-feature-flag' into 'master'

Enable graphql_git_blame feature flag by default

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/139656



Merged-by: Nicolas Dular <ndular@gitlab.com>
Approved-by: Nicolas Dular <ndular@gitlab.com>
Co-authored-by: Jacques <jerasmus@gitlab.com>