Geo: Add bulk registry resync service using new BaseBatchBulkUpdateService

What does this MR do and why?

Add bulk registry resync service

This new service uses the BaseBatchBulkUpdateService introduced in !206339 (merged), which provides:

• Support for composite primary keys and large tables using GitLab's standard keyset pagination
• Consistent batching patterns following GitLab documented batching practices

It will replace the existing BulkMarkPendingService, which has been known to cause bugs in Dedicated.

Next step will be to replace the existing code with this service.

References

• Geo::BulkMarkPendingBatchWorker and BulkMarkVer... (#573613)
• Refactor BulkMarkVerificationPending and BulkMa... (#574035)

MR acceptance checklist

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Related to #574035