Revert "Fix PopupMenuItem & CheckedPopupMenuItem has redundant ListTile padding and update default horizontal padding for Material 3" (#132457)

Reverts flutter/flutter#131609

b/295497265 - This broke Google Testing. We'll need the internal patch
before landing as there's a large number of customer codebases impacted.

dev/tools/gen_defaults/lib/popup_menu_template.dart

@@ -42,9 +42,5 @@ class _${blockName}DefaultsM3 extends PopupMenuThemeData {
 
   @override
   ShapeBorder? get shape => ${shape("md.comp.menu.container")};
-
-  // TODO(tahatesser): This is taken from https://m3.material.io/components/menus/specs
-  // Update this when the token is available.
-  static EdgeInsets menuHorizontalPadding  = const EdgeInsets.symmetric(horizontal: 12.0);
 }''';
 }