Geo: Investigate how to scope checksumming on GitLab.com to a set of orgs

Problem

GitLab.com has massive tables. Some metrics collection queries will not scale that far.

Proposal

We should add the ability for a .com sysadmin to specify a set of organizations to include in checksumming.

How though?

Ideas

It is probably acceptable for a .com SRE to use Rails console to modify the set of organizations for Org Mover purposes.

What might be a really nice to have is if we could extend the feature flag group/project/user scoping to orgs (if that has not already been done), and use it for this purpose.

We could also introduce "selective sync by organization" and extend it to scope the source cell's checksumming activity.