Ensure empty result is returned if specified encounter type is not found

The REST endpoint for encounters does not correctly handle invalid or unauthorized encounterType values. Instead of returning an empty array, the endpoint returns all encounters for the specified patient, ignoring the encounterType filter.

Steps to Reproduce:

1. Call the endpoint with an invalid or unauthorized encounterType value:

   /rest/v1/encounter?patient=<patient-UUID>&encounterType=123

   (Assume 123 is invalid or inaccessible due to privileges.)
   
   

2. Call the endpoint without the encounterType parameter:
   /rest/v1/encounter?patient=<patient-UUID>

I would expect the first query should return an empty array if the encounterType is invalid or the user lacks privileges to view it but both queries return the same result.