Webpublisher - headless publish shouldn't be blocking operation (#5177)

* OP-6239 - headless publish from webpublisher shouldn't be blocking

subprocess.call is blocking, which resulted in UI non responsiveness as it was waiting for publish to finish.

* OP-6239 - revert of typo

openpype/hosts/webpublisher/webserver_service/webpublish_routes.py

@@ -293,7 +293,7 @@ class BatchPublishEndpoint(WebpublishApiEndpoint):
             log.debug("Adding to queue")
             self.resource.studio_task_queue.append(args)
         else:
-            subprocess.call(args)
+            subprocess.Popen(args)
 
         return Response(
             status=200,