squash! caddy-frontend: Put haproxy just before the backend

XXX: Add test with empty server-alias to kick this issue
2 jobs for feature/caddy-frontend-auth-to-backend in 0 seconds
Status Job ID Name Coverage
  External
failed SlapOS.SoftwareReleases.IntegrationTest-luke/feature/caddy-frontend-auth-to-backend

03:03:53

failed SlapOS.SoftwareReleases.IntegrationTest-luke/feature/caddy-frontend-auth-to-backend

02:51:20