It looks like we cannot get the AWSALB from HTTP transformation. It could be product limitation. You can raise a case with GCS, so they can confirm the same.
How are you trying to achieve this? Are you selecting Http Header, and creating a condition that looks for a cookie name value pair? The AWSALB cookie changes value all the time.
Please share more details: request; response etc.
The SetCookie field in the HTTP transformation does hold the cookie sent by a URL for redirect.
You can try to use the same and let us know.
To add to this, only a single redirect is currently possible with the HTTP transformation.
If there is multiple redirects configured for the URL, the SetCookie field has a limitation as it cannot hold more than one cookie sent from the other URL's required for redirect.
In such case, Java transformation is an only option to achieve the requirement.