chore: integ test flakiness

Stacks that are being deployed using roles need to be deleted while the
role is still present. Our test was deleting the role before the stack
was being deleted, and so would fail.

This was a race condition due to a missing `await`.

Fix both.

packages/aws-cdk/test/integ/cli/cli.integtest.ts

@@ -316,6 +316,12 @@ test('deploy with role', async () => {
       options: ['--role-arn', roleArn],
     });
 
+    // Immediately delete the stack again before we delete the role.
+    //
+    // Since roles are sticky, if we delete the role before the stack, subsequent DeleteStack
+    // operations will fail when CloudFormation tries to assume the role that's already gone.
+    await cdkDestroy('test-2');
+
   } finally {
     deleteRole();
   }