Merge branch '407404-remove-feature-flag-ci_builds_columns_size_validation' into 'master'

Remove feature flag ci_builds_columns_size_validation

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/119450



Merged-by: Marius Bobin <mbobin@gitlab.com>
Approved-by: Max Fan <mfan@gitlab.com>
Approved-by: Marius Bobin <mbobin@gitlab.com>
Co-authored-by: Tianwen Chen <tchen@gitlab.com>