Draft: Squash migrations 16-11-stable-ee
Ref: gitlab-org/quality/engineering-productivity/team#564 (closed)
What does this MR do and why?
This MR squashes all migrations before %16.11 as this normally done when GitLab increments by a major version - every migration before the major version release is squashed.
This should improves the slowness of the db:check-schema
job.