action_sheet test: Remove unnecessary teardowns

This teardown is already added in setupToMessageActionSheet, which
is called near the top of every test.

Author: chrisbobbe

test/widgets/action_sheet_test.dart

@@ -102,10 +102,6 @@ void main() {
       return mock;
     }
 
-    tearDown(() async {
-      testBinding.reset();
-    });
-
     Future<void> tapShareButton(WidgetTester tester) async {
       await tester.ensureVisible(find.byIcon(Icons.adaptive.share, skipOffstage: false));
       await tester.tap(find.byIcon(Icons.adaptive.share));
@@ -306,10 +302,6 @@ void main() {
       );
     });
 
-    tearDown(() async {
-      testBinding.reset();
-    });
-
     Future<void> tapCopyButton(WidgetTester tester) async {
       await tester.ensureVisible(find.byIcon(Icons.copy, skipOffstage: false));
       await tester.tap(find.byIcon(Icons.copy));