Other container web service auto detection not working

[bbugh]

The auto detection of another container's web ports does not seem to be working, at least as described in the README. Here is a minimal reproduction:

version: '2'

volumes:
  settings:

services:
  browser:
    restart: always
    image: bh.cr/balenalabs/browser-aarch64
    privileged: true
    volumes:
      - 'settings:/data'
    ports:
      - '5011' # management API (optional)
  web:
    restart: always
    image: nginx:1.25.2
    ports:
      - '80'

1. When starting, it will output:

   [Logs]    [2023-10-03T00:26:12.869Z] [browser] LAUNCH_URL environment variable not set.
   [Logs]    [2023-10-03T00:26:12.871Z] [browser] Looking for local HTTP/S services.
   [Logs]    [2023-10-03T00:26:12.876Z] [browser] No service found on port 80
   [Logs]    [2023-10-03T00:26:12.881Z] [browser] No service found on port 443
   [Logs]    [2023-10-03T00:26:12.886Z] [browser] No service found on port 8080
   [Logs]    [2023-10-03T00:26:12.887Z] [browser] Displaying default HTML page
   

2. If you force it to load web via the API, it will work fine:

   ADDRESS=`sudo balena scan --json | jq -r '.[0].address'`
   curl --data "url=web" http://$ADDRESS:5011/url
   

   This will show the "welcome to nginx" page on the device

3. If you tell it to re-scan via the API, it still won't find the local container.

   curl -X POST http://$ADDRESS:5011/scan
   

   💩

   [Logs]    [2023-10-03T00:34:14.361Z] [browser] LAUNCH_URL environment variable not set.
   [Logs]    [2023-10-03T00:34:14.363Z] [browser] Looking for local HTTP/S services.
   [Logs]    [2023-10-03T00:34:14.369Z] [browser] No service found on port 80
   [Logs]    [2023-10-03T00:34:14.374Z] [browser] No service found on port 443
   [Logs]    [2023-10-03T00:34:14.378Z] [browser] No service found on port 8080
   [Logs]    [2023-10-03T00:34:14.383Z] [browser] Displaying default HTML page
   

4. but if you manually specify LAUNCH_URL to the other container...

   services:
     browser:
       environment:
         LAUNCH_URL: http://web
   

   ... it works: