OZG-6867 Simplify query

src/main/java/de/ozgcloud/admin/organisationseinheit/OrganisationsEinheitRepository.java

@@ -25,6 +25,6 @@ interface OrganisationsEinheitRepository extends MongoRepository<OrganisationsEi
 	@Update("{'$set':  {'syncResult':  'DELETED'}}")
 	void setUnsyncedAsDeleted(long lastSyncTimestamp);
 
-	@Query("{'syncResult': { $eq: null }}")
+	@Query("{'syncResult': null }")
 	Stream<OrganisationsEinheit> findAllWithoutSyncResult();
 }