Geo: Fix undefined separate_verification_state_table?

What does this MR do and why?

Describe in detail what your merge request does and why.

Fixes an undefined method (separate_verification_state_table?) error during VerificationTimeoutWorker jobs.

Fixes #350359 (closed)

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Be running Geo
2. In the secondary site, gdk tail | grep "VerificationTimeoutWorker" see that VerificationTimeoutWorker runs for each replicator every minute, and doesn't error
3. Or run e.g. bin/rails runner "::Geo::VerificationTimeoutWorker.perform_async('snippet_repository')" and see that it doesn't error

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

ee/app/models/concerns/geo/verifiable_model.rb

@@ -53,12 +53,6 @@ def pluck_verifiable_ids_in_range(range)
           .primary_key_in(range)
           .pluck_primary_key
       end
-
-      # @return whether primary checksum data is stored in a table separate
-      #         from the model table
-      def separate_verification_state_table?
-        verification_state_table_name != table_name
-      end
     end
   end
 end