Fix tests for removed Class#initialize

Class#initialize no longer exists, so test_class_initialize falls through
to Module#initialize and raises nothing. Skip the rbs stdlib test that
still exercises Class.allocate and Class#initialize.

Author: jhawthorn

test/ruby/test_class.rb

@@ -83,12 +83,6 @@ def test_class_cmp
     assert_nil(Class.new <=> 1)
   end
 
-  def test_class_initialize
-    assert_raise(TypeError) do
-      Class.new.instance_eval { initialize }
-    end
-  end
-
   def test_instantiate_singleton_class
     c = class << Object.new; self; end
     assert_raise(TypeError) { c.new }

tool/rbs_skip_tests

@@ -42,6 +42,9 @@ test_TOPDIR(RbConfigSingletonTest) `TOPDIR` is `nil` during CI while RBS type is
 # Failing because ObjectSpace.count_nodes has been removed
 test_count_nodes(ObjectSpaceTest)
 
+# Class.allocate and Class#initialize have been removed
+test_initialize(ClassInstanceTest)
+
 ## Unknown failures
 
 # NoMethodError: undefined method 'inspect' for an instance of RBS::UnitTest::Convertibles::ToInt