Fix: Switching to the icingadb backend and searching host/service nod…

…e in add/edit form throws an error

`HostServiceTermValidator`: `$testConfig` requires backend for `MonitoringState::apply()` call.

If the `$testConfig` has no backend set and icingadb is in use, `MonitoringState::__construct($config) => $config->getBackend()` returns an icingadb backend that is not suitable for the `MonitoringState` class.

library/Businessprocess/Web/Form/Validator/HostServiceTermValidator.php

@@ -45,7 +45,8 @@ public function isValid($terms)
         }
 
         $isValid = true;
-        $testConfig = new BpConfig();
+        $testConfig = (new BpConfig())
+            ->setBackend($this->parent->getBpConfig()->getBackend());
 
         foreach ($terms as $term) {
             /** @var Term $term */
@@ -68,7 +69,7 @@ public function isValid($terms)
             }
         }
 
-        if ($this->parent->getBpConfig()->getBackend() instanceof MonitoringBackend) {
+        if ($testConfig->getBackend() instanceof MonitoringBackend) {
             MonitoringState::apply($testConfig);
         } else {
             IcingaDbState::apply($testConfig);