@room messages not handled correcty in settings

I noticed that @room messages are not noisy in element (v1.9.3, 1.9.4), even if they are shown as noisy in the settings.

### Case 1: push rules if @room messages are set to noisy
```
{
"conditions": [
{
"kind": "event_match",
"key": "content.body",
"pattern": "@room"
},
{
"kind": "sender_notification_permission",
"key": "room"
}
],
"actions": [
"notify",
{"set_tweak": "highlight"}
],
"rule_id": ".m.rule.roomnotif",
"default": true,
"enabled": true
}
```

IMHO the `actions` should be
```
"actions": [
"notify",
{"set_tweak": "highlight"},
{"set_tweak": "sound", "value": "default"}
]
```

### Case 2: push rules if @room messages are set to on
```
{
#...
"actions": [
"notify",
{"set_tweak": "highlight", "value": false}
],
"rule_id": ".m.rule.roomnotif",
"default": true,
"enabled": true
}
```

IMHO the `actions` should be
```
"actions": [
"notify",
{"set_tweak": "highlight"},
]
```
as they are in setting "Noisy" yet.

### More thoughts:

- Since @room notification are override rules @room messages are quiet even if rooms are noisy be default, which is very irritating.
- Probably @room messages should be noisy be default, they are only highlighted yet: [synapse baserules](https://github.com/matrix-org/synapse/blob/605921bc6b3d3f48142e3c8b5ddcc6c2a0016062/synapse/push/baserules.py#L269). But this is a server issue of course.