Iteration search uses cadence and iteration titles

Previously only search by iteration title was used. 
Now on the issue page and the list view, we’re searching 
through cadence titles also

Changelog: changed
EE: true

ee/app/assets/javascripts/issues/list/queries/search_iterations.query.graphql

@@ -3,7 +3,7 @@
 query searchIterations($fullPath: ID!, $search: String, $id: ID, $isProject: Boolean = false) {
   group(fullPath: $fullPath) @skip(if: $isProject) {
     id
-    iterations(title: $search, id: $id, includeAncestors: true) {
+    iterations(search: $search, in: [TITLE, CADENCE_TITLE], id: $id, includeAncestors: true) {
       nodes {
         ...Iteration
       }
@@ -11,7 +11,7 @@ query searchIterations($fullPath: ID!, $search: String, $id: ID, $isProject: Boo
   }
   project(fullPath: $fullPath) @include(if: $isProject) {
     id
-    iterations(title: $search, id: $id, includeAncestors: true) {
+    iterations(search: $search, in: [TITLE, CADENCE_TITLE], id: $id, includeAncestors: true) {
       nodes {
         ...Iteration
       }

ee/app/assets/javascripts/sidebar/queries/group_iterations.query.graphql

@@ -4,7 +4,7 @@ query issueIterationsAliased($fullPath: ID!, $title: String, $state: IterationSt
   workspace: group(fullPath: $fullPath) {
     __typename
     id
-    attributes: iterations(title: $title, state: $state) {
+    attributes: iterations(search: $title, in: [TITLE, CADENCE_TITLE], state: $state) {
       nodes {
         ...IterationFragment
         state

ee/spec/features/issues/issue_sidebar_spec.rb

@@ -190,6 +190,27 @@ RSpec.describe 'Issue Sidebar' do
           expect(page.find('[data-testid="select-iteration"]')).to have_content('None')
         end
 
+        context 'when searching iteration by its cadence title', :aggregate_failures do
+          let_it_be(:plan_cadence) { create(:iterations_cadence, title: 'plan cadence', group: group, active: true) }
+          let_it_be(:plan_iteration) { create(:iteration, :with_due_date, iterations_cadence: plan_cadence, start_date: 1.week.from_now) }
+
+          it "returns the correct iteration" do
+            find_and_click_edit_iteration
+
+            within '[data-testid="iteration-edit"]' do
+              page.find(".gl-search-box-by-type-input").send_keys('plan')
+
+              wait_for_requests
+
+              expect(page).to have_text(plan_iteration.title)
+              expect(page).to have_text(plan_iteration.period)
+              expect(page).not_to have_text(iteration_cadence.title)
+              expect(page).not_to have_text(iteration.period)
+              expect(page).not_to have_text(iteration2.period)
+            end
+          end
+        end
+
         it 'does not show closed iterations' do
           find_and_click_edit_iteration
 
@@ -232,6 +253,27 @@ RSpec.describe 'Issue Sidebar' do
           expect(page.find('[data-testid="select-iteration"]')).to have_content('None')
         end
 
+        context 'when searching iteration by its cadence title', :aggregate_failures do
+          let_it_be(:plan_cadence) { create(:iterations_cadence, title: 'plan cadence', group: group, active: true) }
+          let_it_be(:plan_iteration) { create(:iteration, :with_due_date, iterations_cadence: plan_cadence, start_date: 1.week.from_now) }
+
+          it "returns the correct iteration" do
+            find_and_click_edit_iteration
+
+            within '[data-testid="iteration-edit"]' do
+              page.find(".gl-search-box-by-type-input").send_keys('plan')
+
+              wait_for_requests
+
+              expect(page).to have_text(plan_cadence.title)
+              expect(page).to have_text(plan_iteration.period)
+              expect(page).not_to have_text(iteration_cadence.title)
+              expect(page).not_to have_text(iteration.period)
+              expect(page).not_to have_text(iteration2.period)
+            end
+          end
+        end
+
         it 'does not show closed iterations' do
           find_and_click_edit_iteration