[bug][UI]Fixed a bug where the environment name of a task could not be changed when a workflow was created(issue-12457) (#13148)

dolphinscheduler-ui/src/views/projects/task/components/node/fields/use-environment-name.ts

@@ -49,7 +49,7 @@ export function useEnvironmentName(
     if (options.value.length === 0) {
       model.environmentCode = null
     } else {
-      isCreate && (model.environmentCode = options.value[0].value)
+      (isCreate && !model.environmentCode)  && (model.environmentCode = options.value[0].value)
     }
   }