Remove polymorphic check when generating associating methods

When doing a has_many with a polymorphic association, these were previously a generic/untyped collectionproxy. I'm not actually sure that needs to be the case since it appears that you should be getting a CollectionProxy of the model of the association.

lib/tapioca/dsl/compilers/active_record_associations.rb

@@ -287,7 +287,7 @@ def populate_collection_assoc_getter_setter(klass, association_name, reflection)
         def type_for(reflection)
           validate_reflection!(reflection)
 
-          return "T.untyped" if !constant.table_exists? || polymorphic_association?(reflection)
+          return "T.untyped" if !constant.table_exists?
 
           T.must(qualified_name_of(reflection.klass))
         end
@@ -383,33 +383,13 @@ def relation_type_for(reflection)
           validate_reflection!(reflection)
 
           relations_enabled = compiler_enabled?("ActiveRecordRelations")
-          polymorphic_association = !constant.table_exists? || polymorphic_association?(reflection)
 
           if relations_enabled
-            if polymorphic_association
-              "ActiveRecord::Associations::CollectionProxy"
-            else
-              "#{qualified_name_of(reflection.klass)}::#{AssociationsCollectionProxyClassName}"
-            end
-          elsif polymorphic_association
-            "ActiveRecord::Associations::CollectionProxy[T.untyped]"
+            "#{qualified_name_of(reflection.klass)}::#{AssociationsCollectionProxyClassName}"
           else
             "::ActiveRecord::Associations::CollectionProxy[#{qualified_name_of(reflection.klass)}]"
           end
         end
-
-        sig do
-          params(
-            reflection: ReflectionType,
-          ).returns(T::Boolean)
-        end
-        def polymorphic_association?(reflection)
-          if reflection.through_reflection?
-            polymorphic_association?(reflection.source_reflection)
-          else
-            !!reflection.polymorphic?
-          end
-        end
       end
     end
   end

spec/tapioca/dsl/compilers/active_record_associations_spec.rb

@@ -265,7 +265,7 @@ def picture_ids=(ids); end
 
                         # This method is created by ActiveRecord on the `Employee` class because it declared `has_many :pictures`.
                         # 🔗 [Rails guide for `has_many` association](https://guides.rubyonrails.org/association_basics.html#the-has-many-association)
-                        sig { returns(ActiveRecord::Associations::CollectionProxy) }
+                        sig { returns(::Picture::PrivateCollectionProxy) }
                         def pictures; end
 
                         sig { params(value: T::Enumerable[T.untyped]).void }
@@ -1036,7 +1036,7 @@ def picture_ids=(ids); end
 
                         # This method is created by ActiveRecord on the `Employee` class because it declared `has_many :pictures`.
                         # 🔗 [Rails guide for `has_many` association](https://guides.rubyonrails.org/association_basics.html#the-has-many-association)
-                        sig { returns(ActiveRecord::Associations::CollectionProxy[T.untyped]) }
+                        sig { returns(::ActiveRecord::Associations::CollectionProxy[::Picture]) }
                         def pictures; end
 
                         sig { params(value: T::Enumerable[T.untyped]).void }