Geo: Improve tests for Geo verification scopes

Problem

The recent fix in !205710 (merged) revealed that our existing tests for Geo::VerificationState scopes failed to catch a PG::UndefinedColumn error that was occurring in production environments. The needs_reverification scope was generating invalid SQL by trying to query verified_at on the wrong table, but our tests didn't detect this issue.

This suggests our current test suite is likely:

• Using mocks instead of actual database queries
• Not validating the generated SQL
• Not testing the full query execution path

Root Cause

The issue occurred because:

1. The needs_reverification scope was using verified_at directly instead of verification_arel_table[:verified_at]
2. For models with separate state tables (e.g., upload vs upload_state), this generated invalid SQL
3. Our tests didn't catch this because they weren't actually executing the database queries

Proposed Solution

Add comprehensive integration tests that:

1. Test actual SQL execution - Ensure scopes actually run against a real database
2. Verify cross-table relationships - Test models that use separate state tables (uploads, etc.)
3. Test scope combinations - Verify that chained scopes like verification_succeeded.where(...) work correctly
4. Add SQL assertion helpers - Create test utilities to verify generated SQL structure

Example test cases needed:

describe 'needs_reverification scope' do
      before do
        stub_current_geo_node(primary_node)
      end
      let_it_be(:old_verified_upload) do
        create(:upload).tap do |upload|
          upload.verification_succeeded!
          upload.update_column(:verified_at, 20.days.ago)
        end
      end
      let_it_be(:recent_verified_upload) do
        create(:upload).tap do |upload|
          upload.verification_succeeded!
          upload.update_column(:verified_at, 2.days.ago)
        end
      end
      it 'returns uploads verified more than minimum_reverification_interval days ago' do
        expect(Upload.needs_reverification).to contain_exactly(old_verified_upload)
      end
end

Files to update:

• ee/spec/models/concerns/geo/verification_state_spec.rb
• Add new integration test files for specific replicable models
• Consider adding shared examples for verification scope testing

Acceptance Criteria

• Tests execute actual database queries (no mocking of core ActiveRecord methods)
• Tests cover models with separate state tables (Upload, LfsObject, etc.)
• Tests verify that scopes can be chained without SQL errors