Add timeline icon for issue weights

ee/app/helpers/ee/system_note_helper.rb

@@ -13,7 +13,8 @@ module EE
       'issue_added_to_epic' => 'epic',
       'issue_removed_from_epic' => 'epic',
       'issue_changed_epic' => 'epic',
-      'epic_date_changed' => 'calendar'
+      'epic_date_changed' => 'calendar',
+      'weight' => 'scale'
     }.freeze
 
     override :system_note_icon_name

ee/changelogs/unreleased/update-timeline-icon-for-weights.yml

+---
+title: Add timeline icon for issue weights
+merge_request: 7847
+author: George Tsiolis
+type: changed