#48 Use traefik-public as public network and the project specific network only internally

Bump default version for Nginx to 1.21
Bump default version for Varnish to 6.0
Bump default version for Adminer to 4.6
Bump default version for phpMyAdmin to latest
Bump default version for WebGrind to 1
Add setting to turn on/off selenium service
Add service for elasticsearch

Add ahoy dependency

gitlab-ci-cd/drupal#8 No longer call "drush dev on" when downloading DB, we expect config_split to properly configure stages