Merge pull request #26113 from kamipo/use_ar_test_case_instead_of_as_test_case

Use `ActiveRecord::TestCase` rather than `ActiveSupport::TestCase` in AR test cases

activerecord/test/cases/fixtures_test.rb

@@ -280,7 +280,7 @@ class FixturesTest < ActiveRecord::TestCase
   end
 end
 
-class HasManyThroughFixture < ActiveSupport::TestCase
+class HasManyThroughFixture < ActiveRecord::TestCase
   def make_model(name)
     Class.new(ActiveRecord::Base) { define_singleton_method(:name) { name } }
   end

activerecord/test/cases/relation/mutation_test.rb

@@ -2,7 +2,7 @@ require "cases/helper"
 require "models/post"
 
 module ActiveRecord
-  class RelationMutationTest < ActiveSupport::TestCase
+  class RelationMutationTest < ActiveRecord::TestCase
     class FakeKlass < Struct.new(:table_name, :name)
       extend ActiveRecord::Delegation::DelegateCache
       inherited self