Closes #2555 - Fix deleteClassification

Author: ryzheboka

lib/taskana-core/src/main/java/pro/taskana/classification/internal/ClassificationServiceImpl.java

@@ -154,6 +154,7 @@ public void deleteClassification(String classificationId)
         if (isReferentialIntegrityConstraintViolation(e)) {
           throw new ClassificationInUseException(classification, e);
         }
+        throw e;
       }
     } finally {
       taskanaEngine.returnConnection();

rest/taskana-rest-spring/src/main/java/pro/taskana/classification/rest/ClassificationController.java

@@ -334,7 +334,7 @@ public ResponseEntity<ClassificationRepresentationModel> updateClassification(
             content = {@Content(schema = @Schema())})
       })
   @DeleteMapping(path = RestEndpoints.URL_CLASSIFICATIONS_ID)
-  @Transactional(readOnly = true, rollbackFor = Exception.class)
+  @Transactional(rollbackFor = Exception.class)
   public ResponseEntity<ClassificationRepresentationModel> deleteClassification(
       @PathVariable("classificationId") String classificationId)
       throws ClassificationNotFoundException, ClassificationInUseException, NotAuthorizedException {