TF-4367 Remove the duplicated closeEmailDetailedView helper from this mixin.

integration_test/mixin/generate_email_scenario_mixin.dart

@@ -2,7 +2,6 @@ import 'package:flutter_test/flutter_test.dart';
 
 import '../base/base_scenario.dart';
 import '../models/provisioning_email.dart';
-import '../robots/email_robot.dart';
 import 'scenario_utils_mixin.dart';
 
 mixin GenerateEmailScenarioMixin on BaseScenario, ScenarioUtilsMixin {
@@ -22,8 +21,4 @@ mixin GenerateEmailScenarioMixin on BaseScenario, ScenarioUtilsMixin {
     );
     await $.pumpAndTrySettle();
   }
-
-  Future<void> closeEmailDetailedView({required EmailRobot emailRobot}) async {
-    await emailRobot.onTapBackButton();
-  }
 }