[Bug]: Incorrect model endpoint protocol on gateways with LB-terminated TLS

[jvstme]

Steps to reproduce

1. Create a gateway with load_balancer: { type: alb }.
2. Run a service with model: { type: tgi } behind that gateway.
3. Inspect its service.model.base_url.

Actual behaviour

$ dstack run get --json llama31 | jq '.service.model.base_url'
"http://gateway.example.com"

Expected behaviour

$ dstack run get --json llama31 | jq '.service.model.base_url'
"https://gateway.example.com"

dstack version

0.22.0

Server logs

Additional information

No response