Fix Rubocop offenses

lib/gitlab/background_migration/prepare_untracked_uploads.rb

@@ -97,7 +97,7 @@ module Gitlab
               end
 
         timestamp = Time.now.utc.iso8601
-        sql = ActiveRecord::Base.send(:sanitize_sql_array, [sql, file_path, timestamp, timestamp])
+        sql = ActiveRecord::Base.send(:sanitize_sql_array, [sql, file_path, timestamp, timestamp]) # rubocop:disable GitlabSecurity/PublicSend
         ActiveRecord::Base.connection.execute(sql)
       end
 

spec/lib/gitlab/background_migration/populate_untracked_uploads_spec.rb

@@ -215,7 +215,6 @@ describe Gitlab::BackgroundMigration::PopulateUntrackedUploads::UntrackedFile do
 
     context 'for a project Markdown attachment (notes, issues, MR descriptions) file path' do
       let(:model) { create(:project) }
-      let(:expected_upload_attrs) { {} }
 
       # UntrackedFile.path is different than Upload.path
       let(:untracked_file) { create_untracked_file("/#{model.full_path}/#{model.uploads.first.path}") }
@@ -228,7 +227,7 @@ describe Gitlab::BackgroundMigration::PopulateUntrackedUploads::UntrackedFile do
         untracked_file
 
         # Save the expected upload attributes
-        expected_upload_attrs = model.reload.uploads.first.attributes.slice('path', 'uploader', 'size', 'checksum')
+        @expected_upload_attrs = model.reload.uploads.first.attributes.slice('path', 'uploader', 'size', 'checksum')
 
         # Untrack the file
         model.reload.uploads.delete_all
@@ -239,8 +238,7 @@ describe Gitlab::BackgroundMigration::PopulateUntrackedUploads::UntrackedFile do
           untracked_file.add_to_uploads
         end.to change { model.reload.uploads.count }.from(0).to(1)
 
-        hex_secret = untracked_file.path.match(/\/(\h+)\/rails_sample.jpg/)[1]
-        expect(model.uploads.first.attributes).to include(expected_upload_attrs)
+        expect(model.uploads.first.attributes).to include(@expected_upload_attrs)
       end
     end
   end

spec/migrations/track_untracked_uploads_spec.rb

@@ -42,7 +42,7 @@ describe TrackUntrackedUploads, :migration, :sidekiq, :temp_table_may_drop do
     it 'has a path field long enough for really long paths' do
       migrate!
 
-      component = 'a'*255
+      component = 'a' * 255
 
       long_path = [
         'uploads',