Same DNS name for multiple clusters

[mosabua]

With the recent development in Trino for X-Forwarded-Prefix it should be possible to run Trino Gateway in front of multiple Trino clusters and use a single domain name for all clusters.

See trinodb/trino#22227 and https://trino.io/docs/current/release/release-452.html

We need to verify this to be true, potentially upgrade airlift, and document how to set it all up to get it working.

Trino clusters definitely would have to use 452 or newer.