Merge branch 'lw/341085-gitlab-subscriptions-cleanup-trial-date-attributes' into 'master'

Clean gitlab subscription trial date attributes

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/169196



Merged-by: Tiger Watson <twatson@gitlab.com>
Approved-by: Tiger Watson <twatson@gitlab.com>
Reviewed-by: Tiger Watson <twatson@gitlab.com>
Reviewed-by: Sincheol (David) Kim <dkim@gitlab.com>
Co-authored-by: Lukas Wanko <lwanko@gitlab.com>