Run batched migrations on self-managed instances

Merged Heinrich Lee Yu requested to merge enable-batched-migrations-for-self-hosted into master

What does this MR do?

This enables batched background migrations for all instances. We need them to be completed before we can swap columns to bigint.

Without this cron job running, upgrading to a version that has the bigint swap migrations would fail.

See #288005 (comment 614744621) / gitlab-org/charts/gitlab#2785 (closed) / #334996 (closed)

Screenshots (strongly suggested)

Does this MR meet the acceptance criteria?

Conformity

Availability and Testing

Security

Does this MR contain changes to processing or storing of credentials or tokens, authorization and authentication methods or other items described in the security review guidelines? If not, then delete this Security section.

  • Label as security and @ mention @gitlab-com/gl-security/appsec
  • The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
  • Security reports checked/validated by a reviewer from the AppSec team
Edited by Heinrich Lee Yu