fix: incorrect rules around family insurances

addresses #869dr80qj

tests/Form/Service/ParticipantInsuranceFieldHandlerTest.php

@@ -31,6 +31,8 @@ class ParticipantInsuranceFieldHandlerTest extends TestCase
         // Mock price calculator to return a default price
         $this->priceCalculatorService->method('calculateIndividualParticipantPriceExcludingInsurance')
             ->willReturn(500.0);
+        $this->priceCalculatorService->method('resolveInsuranceTravelPrice')
+            ->willReturn(500.0);
 
         $this->handler = new ParticipantInsuranceFieldHandler($this->insuranceService, $this->priceCalculatorService);
     }