Fix empty icon for iteration system notes

Shows the iteration icon for iteration-related system notes

ee/app/helpers/ee/system_note_helper.rb

@@ -14,6 +14,7 @@ module EE
       'issue_removed_from_epic' => 'epic',
       'issue_changed_epic' => 'epic',
       'epic_date_changed' => 'calendar',
+      'iteration' => 'iteration',
       'weight' => 'weight',
       'relate_epic' => 'epic',
       'unrelate_epic' => 'epic',

ee/changelogs/unreleased/262660-fix-iteration-system-notes-icon.yml

+---
+title: Fix icon for iteration-related system notes
+merge_request: 45642
+author:
+type: fixed

ee/spec/helpers/ee/system_note_helper_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe SystemNoteHelper do
+  describe '.system_note_icon_name' do
+    subject(:system_note_icon_name) { helper.system_note_icon_name(note) }
+
+    context 'for an iteration note' do
+      let(:iteration_event) { build_stubbed(:resource_iteration_event) }
+      let(:note) { IterationNote.from_event(iteration_event, resource: iteration_event.issue) }
+
+      it 'returns the iteration icon name' do
+        expect(system_note_icon_name).to eq('iteration')
+      end
+    end
+  end
+end