Merge pull request #28687 from kamipo/fix_warning_already_initialized_constant

Fix `warning: already initialized constant HashWithIndifferentAccessTest::HashWithIndifferentAccess`

activesupport/test/hash_with_indifferent_access_test.rb

@@ -675,7 +675,6 @@ def initialize(*)
       assert_includes yaml_output, "hash"
     end
   end
-  HashWithIndifferentAccess = ActiveSupport::HashWithIndifferentAccess
 
   def test_should_use_default_proc_for_unknown_key
     hash_wia = HashWithIndifferentAccess.new { 1 + 2 }