Code behaves correct now, the test wasn't up to date. However, it wasn't
failing as the object has been changed at runtime while the (at that time
already filled) internal lookup cache wasn't cleared. Woulnd't have had any
effect on real-world environments. However, it's fixed right now.
Apply for rules are defined through `apply_for` property
Only Array custom variables will be eligible in apply_for dropdown.
API Example:
```bash
./director-curl POST director/service?name=my_service '{"apply_for": "for (checked_tcp_port in host.vars.checked_tcp_ports)" }'
```
Will render as:
```
apply Service "my_service" for (checked_tcp_port in host.vars.checked_tcp_ports) {
...
}
```
Feature: https://dev.icinga.org/issues/11976
Depends-On: https://github.com/Icinga/icingaweb2-module-director/pull/20
refs #11976
Thomas Gelf
Corentin Ardeois