3.38 / 3.10 (#2742)

This PR makes samples pass CI when 3.10 is released.

## Pre-launch Checklist

- [x] I read the [Flutter Style Guide] _recently_, and have followed its
advice.
- [x] I signed the [CLA].
- [x] I read the [Contributors Guide].
- [x] I have added sample code updates to the [changelog].
- [x] I updated/added relevant documentation (doc comments with `///`).

testing_app/lib/screens/favorites.dart

@@ -41,8 +41,7 @@ class FavoriteItemTile extends StatelessWidget {
       padding: const EdgeInsets.all(8.0),
       child: ListTile(
         leading: CircleAvatar(
-          backgroundColor:
-              Colors.primaries[itemNo % Colors.primaries.length],
+          backgroundColor: Colors.primaries[itemNo % Colors.primaries.length],
         ),
         title: Text('Item $itemNo', key: Key('favorites_text_$itemNo')),
         trailing: IconButton(

testing_app/lib/screens/home.dart

@@ -52,8 +52,7 @@ class ItemTile extends StatelessWidget {
       padding: const EdgeInsets.all(8.0),
       child: ListTile(
         leading: CircleAvatar(
-          backgroundColor:
-              Colors.primaries[itemNo % Colors.primaries.length],
+          backgroundColor: Colors.primaries[itemNo % Colors.primaries.length],
         ),
         title: Text('Item $itemNo', key: Key('text_$itemNo')),
         trailing: IconButton(