chore: call refresh after the subscription is ready, fixes CI (#7542)

LivePreview data was stale if the user entered data while the socket
connection was being established. This change ensures fresh data is
fetched after the connection is established.

This is easy to see when turning on 4G connection and in CI, where it is
especially slow.

test/live-preview/app/live-preview/_api/getDoc.ts

@@ -1,10 +1,10 @@
-import type { Where } from 'payload'
+import type { CollectionSlug, Where } from 'payload'
 
 import config from '@payload-config'
 import { getPayloadHMR } from '@payloadcms/next/utilities/getPayloadHMR.js'
 
 export const getDoc = async <T>(args: {
-  collection: string
+  collection: CollectionSlug
   depth?: number
   draft?: boolean
   slug?: string