[Discover] Column sort URL parameters are broken in 7.8+

[lukeelmers]

Summary

In 6.8 (and possibly later) columns in Discover were sorted based on this URL parameter:
sort:!('@timestamp',desc))

Strangely, in 7.8 and later you need to wrap the sort again to get it to work as expected:
sort:!(!('@timestamp',desc)))

In particular this is an issue for folks who have created short URLs to Discover in 6.8 and updated to 7.8 -- suddenly their sorts are broken.

To Reproduce

1. Spin up a 6.8.12 cluster in Elastic Cloud
2. Add two documents in a new index:

PUT test/_doc
{
  "name":"Tobias",
  "age": 34,
  "height": 178,
  "@timestamp": "2020-09-02T19:43:00.000Z"
}

PUT test/_doc
{
  "name":"Kalle",
  "age": 44,
  "height": 158,
  "@timestamp": "2020-09-02T19:40:20.000Z"
}

3. Create index pattern called test*, Time field set to @timestamp.
4. Go to discover, add column "age"
5. Click Share -> Permalinks -> Snapshot -> Short URL -> Copy Link
6. Paste the url in a text editor. Notice that the url ends with sort:!('@timestamp',desc))
7. Upgrade the cluster to 7.8.1
8. Paste the short url in the browser and hit Enter
9. Add a new column, for example "name".
10. Click refresh. The posts are now in reversed order. If they are not you can also go to Inspect -> Request and see that sort parameter is empty.
11. Manually change the sort in the URL to sort:!(!('@timestamp',desc))). Now everything works as it originally did in 6.8.

This issue is also present on 7.9

Workarounds

1. Creating new short URLs after manually changing the sort as described in 11 above.
2. An _update_by_query on the .kibana index which is risky and has potential to break all URLs if not done carefully:

POST .kibana/_update_by_query
{
  "script": {
    "source": "ctx._source.url.url = ctx._source.url.url.replace('!(%27@timestamp%27,desc)', '!(!(%27@timestamp%27,desc))')",
    "lang": "painless"
  },
  "query": {
    "match": {
      "type": "url"
    }
  }
}

[elasticmachine]

Pinging @elastic/kibana-app (Team:KibanaApp)

[kertal]

The reason for the change of the sort parameter is the introduction of multipart in #41918, looking into the details, if that already broke in 7.4 or after

[kertal]

I can confirm that this broke in 7.4, working on a fix