Allow string in distinct_count cop

ee/lib/ee/gitlab/usage_data.rb

@@ -393,7 +393,6 @@ module EE
         # rubocop:enable CodeReuse/ActiveRecord
 
         # rubocop:disable CodeReuse/ActiveRecord
-        # rubocop: disable UsageData/DistinctCountByLargeForeignKey
         def projects_with_sectional_code_owner_rules(time_period)
           distinct_count(
             ::ApprovalMergeRequestRule
@@ -406,7 +405,6 @@ module EE
             finish: project_maximum_id
           )
         end
-        # rubocop: enable UsageData/DistinctCountByLargeForeignKey
         # rubocop:enable CodeReuse/ActiveRecord
       end
     end

rubocop/cop/usage_data/distinct_count_by_large_foreign_key.rb

@@ -31,7 +31,7 @@ module RuboCop
         private
 
         def allowed_foreign_key?(key)
-          key.type == :sym && allowed_foreign_keys.include?(key.value)
+          [:sym, :str].include?(key.type) && allowed_foreign_keys.include?(key.value.to_sym)
         end
 
         def allowed_foreign_keys

rubocop/rubocop-usage-data.yml

@@ -44,3 +44,4 @@ UsageData/DistinctCountByLargeForeignKey:
     - :project_id
     - :issue_id
     - :merge_request_id
+    - :merge_requests.target_project_id

spec/rubocop/cop/usage_data/distinct_count_by_large_foreign_key_spec.rb

@@ -10,7 +10,7 @@ require_relative '../../../../rubocop/cop/usage_data/distinct_count_by_large_for
 RSpec.describe RuboCop::Cop::UsageData::DistinctCountByLargeForeignKey, type: :rubocop do
   include CopHelper
 
-  let(:allowed_foreign_keys) { %i[author_id user_id] }
+  let(:allowed_foreign_keys) { [:author_id, :user_id, :'merge_requests.target_project_id'] }
 
   let(:config) do
     RuboCop::Config.new('UsageData/DistinctCountByLargeForeignKey' => {
@@ -29,10 +29,16 @@ RSpec.describe RuboCop::Cop::UsageData::DistinctCountByLargeForeignKey, type: :r
   end
 
   context 'when calling by allowed key' do
-    it 'does not register an offence' do
+    it 'does not register an offence with symbol' do
       inspect_source('distinct_count(Issue, :author_id)')
 
       expect(cop.offenses).to be_empty
     end
+
+    it 'does not register an offence with string' do
+      inspect_source("distinct_count(Issue, 'merge_requests.target_project_id')")
+
+      expect(cop.offenses).to be_empty
+    end
   end
 end