Revert artifact locking refactor
This reverts !30741 (merged) but retains the migrations to avoid churn, since this was causing gitlab-com/gl-infra/production#2407 (closed).
Edited by Stan Hu
This reverts !30741 (merged) but retains the migrations to avoid churn, since this was causing gitlab-com/gl-infra/production#2407 (closed).