Add a thin encapsulation around .pluck(:project_id)

ee/app/finders/geo/legacy_project_registry_pending_verification_finder.rb

@@ -70,11 +70,11 @@ module Geo
           .or(legacy_repository_state_table[:wiki_verification_checksum].not_eq(nil)
             .and(project_registry_sync_table[:want_to_sync_wiki].eq(true))))
         .limit(batch_size)
-        .pluck(:project_id)
+        .pluck_project_key
 
       legacy_inner_join_registry_ids(
-        Geo::ProjectRegistry.where(project_id: project_ids),
-        current_node.projects.pluck(:id),
+        Geo::ProjectRegistry.project_id_in(project_ids),
+        current_node.projects.pluck_primary_key,
         Geo::ProjectRegistry,
         foreign_key: :project_id
       )

ee/app/models/geo/project_registry.rb

@@ -31,6 +31,10 @@ class Geo::ProjectRegistry < Geo::BaseRegistry
   scope :wiki_checksum_mismatch, -> { where(wiki_checksum_mismatch: true) }
   scope :with_routes, -> { includes(project: :route).includes(project: { namespace: :route }) }
 
+  def self.project_id_in(ids)
+    where(project_id: ids)
+  end
+
   def self.failed
     repository_sync_failed = arel_table[:repository_retry_count].gt(0)
     wiki_sync_failed = arel_table[:wiki_retry_count].gt(0)

ee/app/models/project_repository_state.rb

@@ -18,4 +18,8 @@ class ProjectRepositoryState < ApplicationRecord
   scope :verification_failed_wikis, -> { where.not(last_wiki_verification_failure: nil) }
   scope :verified_repos, -> { where.not(repository_verification_checksum: nil).where(last_repository_verification_failure: nil) }
   scope :verified_wikis, -> { where.not(wiki_verification_checksum: nil).where(last_wiki_verification_failure: nil) }
+
+  def self.pluck_project_key
+    where(nil).pluck(:project_id)
+  end
 end