Remove version conditional for calling GC.disable

Author: rafaelfranca

activerecord/test/cases/finder_test.rb

@@ -55,7 +55,7 @@ def test_find_passing_active_record_object_is_deprecated
   end
 
   def test_symbols_table_ref
-    gc_disabled = GC.disable if RUBY_VERSION >= '2.2.0'
+    gc_disabled = GC.disable
     Post.where("author_id" => nil)  # warm up
     x = Symbol.all_symbols.count
     Post.where("title" => {"xxxqqqq" => "bar"})