API: Updating rules via streams api has no effect

Creating streams including rules works. An update of the streams also works. An update of the rules in the streams does not work.

## Expected Behavior
PUT on /streams/{streamId} should update stream rules.

## Current Behavior
Model (from api docs):
```
urn:jsonschema:org:graylog2:rest:resources:streams:responses:StreamResponse {
id (string, optional),
creator_user_id (string, optional),
outputs (array[object], optional),
matching_type (string, optional),
description (string, optional),
created_at (string, optional),
disabled (boolean, optional),
rules (array[object], optional),
alert_conditions (array[object], optional),
alert_receivers (object, optional),
title (string, optional),
content_pack (string, optional),
is_default (boolean, optional),
remove_matches_from_default_stream (boolean, optional),
index_set_id (string, optional)
}
```

JSON body:
```
{
"id": "***",
"creator_user_id": "***",
"outputs": [],
"matching_type": "AND",
"description": "***",
"created_at": "2020-07-23T08:02:50.822Z",
"disabled": false,
"rules": [
{
"field": "source",
"stream_id": "***",
"description": null,
"id": "***",
"type": 2,
"inverted": false,
"value": "***"
}
],
"alert_conditions": [],
"alert_receivers": {
"emails": [],
"users": []
},
"title": "***",
"content_pack": null,
"remove_matches_from_default_stream": true,
"index_set_id": "***",
"is_default": false
}
```

All changes in rules are not executed. The higher-level ones will be executed.

Response code: 200

Response headers:
```
{"Access-Control-Allow-Credentials":"true","Access-Control-Allow-Headers":"Authorization, Content-Type, X-Graylog-No-Session-Extension, X-Requested-With, X-Requested-By","Access-Control-Allow-Methods":"GET, POST, PUT, DELETE, OPTIONS","Access-Control-Allow-Origin":"https://***","Access-Control-Max-Age":"600","Content-Encoding":"gzip","Content-Type":"application/json","Date":"Thu, 23 Jul 2020 09:26:03 GMT","Server":"***","Vary":"Accept-Encoding","X-Firefox-Spdy":"h2","X-Graylog-Node-Id":"***","X-Runtime-Microseconds":"60936"}
```

## Steps to Reproduce (for bugs)

1. Create an stream with rules
2. Update the stream rules

## Your Environment

* Graylog Version: 3.3.2+ade4779
* Elasticsearch Version: 6.3.0
* MongoDB Version: 4.2.1
* Operating System: Debian 10 64
* Browser version: N/A

Thank you very much, if you need further information, I can give it to you later.