Fix override of sort_direction_icon in ee sorting_helper

Fixes a special case for sorting by weight, closes #37067

ee/app/helpers/ee/sorting_helper.rb

@@ -55,10 +55,10 @@ module EE
       }.merge(super)
     end
 
-    override :issuable_sort_icon_suffix
-    def issuable_sort_icon_suffix(sort_value)
+    override :sort_direction_icon
+    def sort_direction_icon(sort_value)
       if sort_value == sort_value_weight
-        'lowest'
+        'sort-lowest'
       else
         super
       end

ee/changelogs/unreleased/37067-sort-direction-icon.yml

+---
+title: Fix sort icon direction when sorting by weight
+merge_request: 21447
+author: Jan Beckmann
+type: fixed

ee/spec/helpers/ee/sorting_helper_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe SortingHelper do
+  describe '#sort_direction_icon' do
+    it 'returns lowest for weight' do
+      expect(sort_direction_icon('weight')).to eq('sort-lowest')
+    end
+
+    it 'behaves like non-ee for other sort values' do
+      expect(sort_direction_icon('milestone')).to eq('sort-lowest')
+      expect(sort_direction_icon('last_joined')).to eq('sort-highest')
+    end
+  end
+end