chore: dart format and remove unused variables

Author: khatruong2009

packages/auth/amplify_auth_cognito/example/integration_test/mfa_email_totp_optional_test.dart

@@ -392,9 +392,10 @@ void main() {
           );
           check(signInRes.nextStep.signInStep)
               .equals(AuthSignInStep.confirmSignInWithEmailMfaCode);
-          check(signInRes.nextStep.codeDeliveryDetails).isNotNull()
-            .has((d) => d.deliveryMedium, 'deliveryMedium')
-                .equals(DeliveryMedium.email);
+          check(signInRes.nextStep.codeDeliveryDetails)
+              .isNotNull()
+              .has((d) => d.deliveryMedium, 'deliveryMedium')
+              .equals(DeliveryMedium.email);
 
           final confirmRes = await Amplify.Auth.confirmSignIn(
             confirmationValue: await otpResult.code,

packages/auth/amplify_auth_cognito/example/integration_test/mfa_username_login_required_test.dart

@@ -42,11 +42,11 @@ void main() {
               'When an email is registered and the userpool has email MFA enabled, Cognito will automatically enable email MFA as the preferred MFA method.',
         ).equals(AuthSignInStep.continueSignInWithMfaSetupSelection);
 
-        final selectRes = await Amplify.Auth.confirmSignIn(
+        await Amplify.Auth.confirmSignIn(
           confirmationValue: 'EMAIL',
         );
 
-        final setupRes = await Amplify.Auth.confirmSignIn(
+        await Amplify.Auth.confirmSignIn(
           confirmationValue: email,
         );
 
@@ -167,11 +167,11 @@ void main() {
                 'When both EMAIL and TOTP are enabled but email attribute isnt verified, choose an mfa method to set up.',
           ).equals(AuthSignInStep.continueSignInWithMfaSetupSelection);
 
-          final selectRes = await Amplify.Auth.confirmSignIn(
+          await Amplify.Auth.confirmSignIn(
             confirmationValue: 'EMAIL',
           );
 
-          final setupRes = await Amplify.Auth.confirmSignIn(
+          await Amplify.Auth.confirmSignIn(
             confirmationValue: email,
           );
 

packages/authenticator/amplify_authenticator_test/lib/src/pages/email_mfa_setup_page.dart

@@ -31,8 +31,10 @@ class EmailMfaSetupPage extends AuthenticatorPage {
     final currentScreen = tester.widget<AuthenticatorScreen>(
       find.byType(AuthenticatorScreen),
     );
-    expect(currentScreen.step,
-        equals(AuthenticatorStep.continueSignInWithEmailMfaSetup),);
+    expect(
+      currentScreen.step,
+      equals(AuthenticatorStep.continueSignInWithEmailMfaSetup),
+    );
   }
 
   /// When I enter an email