Fix memory leak in Form (#132987)

Diposes some restorable variables that weren't disposed before.

packages/flutter/lib/src/widgets/form.dart

@@ -573,6 +573,13 @@ class FormFieldState<T> extends State<FormField<T>> with RestorationMixin {
     super.deactivate();
   }
 
+  @override
+  void dispose() {
+    _errorText.dispose();
+    _hasInteractedByUser.dispose();
+    super.dispose();
+  }
+
   @override
   Widget build(BuildContext context) {
     if (widget.enabled) {

packages/flutter/test/material/text_form_field_test.dart

@@ -247,9 +247,6 @@ void main() {
   },
     variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.linux, TargetPlatform.windows }),
     skip: kIsWeb, // [intended] we don't supply the cut/copy/paste buttons on the web.
-    // TODO(polina-c): remove after fixing
-    // https://github.com/flutter/flutter/issues/130467
-    leakTrackingTestConfig: const LeakTrackingTestConfig(allowAllNotDisposed: true, allowAllNotGCed: true),
   );
 
   testWidgetsWithLeakTracking(