Apply DB maintainer suggestions

- Remove redundant where condition
- Add spec coverage for updating title to a blank value

ee/app/models/ee/issue.rb

@@ -42,7 +42,7 @@ module EE
       scope :in_iteration_scope, ->(iteration_scope) { joins(:iteration).merge(iteration_scope) }
       scope :in_iteration_cadences, ->(iteration_cadences) { joins(:iteration).where(sprints: { iterations_cadence_id: iteration_cadences }) }
       scope :with_iteration_title, ->(iteration_title) { joins(:iteration).where(sprints: { title: iteration_title }) }
-      scope :without_iteration_title, ->(iteration_title) { left_outer_joins(:iteration).where('sprints.title IS DISTINCT FROM ? OR sprints.id IS NULL', iteration_title) }
+      scope :without_iteration_title, ->(iteration_title) { left_outer_joins(:iteration).where('sprints.title IS DISTINCT FROM ?', iteration_title) }
       scope :on_status_page, -> do
         joins(project: :status_page_setting)
         .where(status_page_settings: { enabled: true })

ee/spec/models/ee/iteration_spec.rb

@@ -72,6 +72,16 @@ RSpec.describe Iteration do
     it { is_expected.to eq('Sep 30, 2022 - Oct 4, 2022') }
   end
 
+  describe '#title' do
+    let_it_be(:iteration) { create(:iteration, title: "foobar", group: create(:group)) }
+
+    it 'updates title to a blank value', :aggregate_failures do
+      iteration.update!(title: "")
+
+      expect(iteration.title).to be_nil
+    end
+  end
+
   describe '.reference_pattern' do
     let_it_be(:group) { create(:group) }
     let_it_be(:iteration_cadence) { create(:iterations_cadence, group: group) }