fix(Redis Trigger Node): Activating a workflow with a Redis trigger fails (#8129)

## Summary
> Describe what the PR does and how to test. Photos and videos are
recommended.

We were awaiting for the promise to resolve before returning. Because
the trigger method does not return until the first message is received
or the connection errors, the requests that actives the workflows did
not respond making the activation button irresponsive.

Without the change:

https://www.loom.com/share/769b26d5d4ee407e999344fab3905eae

With the change:

https://www.loom.com/share/d1691ee1941248bc97f2ed97b0c129a3

## Related tickets and issues

https://linear.app/n8n/issue/ADO-895/activating-a-workflow-with-a-redis-trigger-fails


## Review / Merge checklist
- [x] PR title and summary are descriptive. **Remember, the title
automatically goes into the changelog. Use `(no-changelog)` otherwise.**
([conventions](https://github.com/n8n-io/n8n/blob/master/.github/pull_request_title_conventions.md))
- [x] [Docs updated](https://github.com/n8n-io/n8n-docs) or follow-up
ticket created.

packages/nodes-base/nodes/Redis/RedisTrigger.node.ts

@@ -118,7 +118,7 @@ export class RedisTrigger implements INodeType {
 		};
 
 		if (this.getMode() === 'trigger') {
-			await manualTriggerFunction();
+			void manualTriggerFunction();
 		}
 
 		async function closeFunction() {