Fix broken test

The 2 tests can be merged for simplicity,
as the second test is testing the
internal implementation.

spec/lib/gitlab/background_migration/migrate_pages_metadata_spec.rb

@@ -7,7 +7,7 @@ RSpec.describe Gitlab::BackgroundMigration::MigratePagesMetadata, schema: 201909
 
   subject(:migrate_pages_metadata) { described_class.new }
 
-  describe '#perform_on_relation' do
+  describe '#perform' do
     let(:namespaces) { table(:namespaces) }
     let(:builds) { table(:ci_builds) }
     let(:pages_metadata) { table(:project_pages_metadata) }
@@ -23,9 +23,9 @@ RSpec.describe Gitlab::BackgroundMigration::MigratePagesMetadata, schema: 201909
       not_migrated_no_pages = projects.create!(namespace_id: namespace.id, name: 'Not Migrated No Pages')
       project_not_in_relation_scope = projects.create!(namespace_id: namespace.id, name: 'Other')
 
-      projects_relation = projects.where(id: [not_migrated_with_pages, not_migrated_no_pages, migrated])
+      ids = [not_migrated_no_pages.id, not_migrated_with_pages.id, migrated.id]
 
-      migrate_pages_metadata.perform_on_relation(projects_relation)
+      migrate_pages_metadata.perform(ids.min, ids.max)
 
       expect(pages_metadata.find_by_project_id(not_migrated_with_pages.id).deployed).to eq(true)
       expect(pages_metadata.find_by_project_id(not_migrated_no_pages.id).deployed).to eq(false)
@@ -33,12 +33,4 @@ RSpec.describe Gitlab::BackgroundMigration::MigratePagesMetadata, schema: 201909
       expect(pages_metadata.find_by_project_id(project_not_in_relation_scope.id)).to be_nil
     end
   end
-
-  describe '#perform' do
-    it 'creates relation and delegates to #perform_on_relation' do
-      expect(migrate_pages_metadata).to receive(:perform_on_relation).with(projects.where(id: 3..5))
-
-      migrate_pages_metadata.perform(3, 5)
-    end
-  end
 end