Update Preloader::Assocation::LoaderQuery to compare using scope.name

Using scope.table_name can result in missing preloaded associations
if you're preloading polymorphic associations across multiple databases
with the same table names. By using the scope name, we're comparing class names,
which are guaranteed to be different even if the table_name is equivalent.

Author: summera

activerecord/lib/active_record/associations/preloader/association.rb

@@ -16,12 +16,12 @@ def initialize(scope, association_key_name)
 
           def eql?(other)
             association_key_name == other.association_key_name &&
-              scope.table_name == other.scope.table_name &&
+              scope.name == other.scope.name &&
               scope.values_for_queries == other.scope.values_for_queries
           end
 
           def hash
-            [association_key_name, scope.table_name, scope.values_for_queries].hash
+            [association_key_name, scope.name, scope.values_for_queries].hash
           end
 
           def records_for(loaders)