Geo: Refactor: Rename VerificationWorker

What does this MR do?

Only a refactor, no change in behavior.

This worker is renamed because the logic can be the same whether it is running on a primary Geo node or a secondary Geo node. Also it can be used for Blobs or Repositories.

All we will need to do is make sure calculate_checksum! does the right thing, and only enqueue it when appropriate. Pushing the logic out of this worker will avoid a ton of unnecessary boilerplate. That work will be following on this MR shortly.

Related: #13981 (closed), #13839 (closed)

Does this MR meet the acceptance criteria?

Conformity

• Code review guidelines
• Style guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.