merge: #9966

9966: Fix NPE on sendCorrelateCommand() side-effect r=remcowesterhoud a=remcowesterhoud

## Description

<!-- Please explain the changes you made here. -->
With the engine abstraction topic the response writer is already getting flushed in the `executeSideEffects()` method of the `ProcessingStateMachine`. Flushing a second time here causes NullPointerExceptions.


## Related issues

<!-- Which issues are closed by this PR or are related -->

closes #9860



Co-authored-by: Remco Westerhoud <remco@westerhoud.nl>

engine/src/main/java/io/camunda/zeebe/engine/processing/message/MessagePublishProcessor.java

@@ -177,19 +177,15 @@ private void correlateToMessageStartEvents(final MessageRecord messageRecord) {
   }
 
   private boolean sendCorrelateCommand() {
-
-    final var success =
-        correlatingSubscriptions.visitSubscriptions(
-            subscription ->
-                commandSender.correlateProcessMessageSubscription(
-                    subscription.getProcessInstanceKey(),
-                    subscription.getElementInstanceKey(),
-                    subscription.getBpmnProcessId(),
-                    messageRecord.getNameBuffer(),
-                    messageKey,
-                    messageRecord.getVariablesBuffer(),
-                    messageRecord.getCorrelationKeyBuffer()));
-
-    return success && responseWriter.flush();
+    return correlatingSubscriptions.visitSubscriptions(
+        subscription ->
+            commandSender.correlateProcessMessageSubscription(
+                subscription.getProcessInstanceKey(),
+                subscription.getElementInstanceKey(),
+                subscription.getBpmnProcessId(),
+                messageRecord.getNameBuffer(),
+                messageKey,
+                messageRecord.getVariablesBuffer(),
+                messageRecord.getCorrelationKeyBuffer()));
   }
 }