Call RenameRepository and RemoveRepository

What does this MR do?

Refactor shell.rb to call RenameRepository and RemoveRepository. We are trying to get rid of all calls to the NamespaceService.

Since shell.rb calls RenameRepository, which also does a mkdir -p before it moves the repository, we can also get rid of some calls to add_namespace in ee/app/services/geo/repository_base_sync_service.rb

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Performance and Testing

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

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• 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