As we now run on the DNS of AWS itself, there is no longer any
need for aws.openttd.org to exist. Before it was used to CNAME
from the old DNS to AWS DNS, so:

 www.openttd.org -> www.aws.openttd.org -> ALB

As AWS services update the AWS DNS, that was needed in order to
work with deployments from CDK. As we are now migrated to Route53
as our primary DNS, nothing is CNAMEing to aws.openttd.org anymore.

Although it can be useful to have sessions to be sticky, it also
means we get questions why we have a cookie in all our requests.
As we rather prevent showing a cookiebanner telling about it, it
is just easier to remove it.

During a deployment a user can flip/flop between a new version
of the site and an old version, which might give unexpected
results. As these moments are far apary, the impact should be
very very minimal.