'showCallButtonsInComposer' option not hiding the 'call button' in header

### Steps to reproduce

1. add in the `config.json` the key `setting_defaults.showCallButtonsInComposer` with value `false`
2. Connect to the element-web and check a private room or channel
3. The call button is still here in the upper right corner in the header

Here is the `config.json` used in case it helps :
```json
{
"default_server_config": {
"m.homeserver": {
"base_url": "https://synapse.local"
}
},
"logout_redirect_url": "https://auth.local/realms/local/protocol/openid-connect/logout?post_logout_redirect_uri=https%3A%2F%2Felement.local%2F%23%2Flogin&client_id=synapse",
"sso_redirect_options": {
"immediate": false,
"on_welcome_page": false,
"on_login_page": false
},
"setting_defaults": {
"showCallButtonsInComposer": false
}
}
```

### Outcome

According to the [`Settings.tsx`](https://github.com/element-hq/element-web/blob/82957507d078a9fcb26001792cb703c4ec6bedb4/src/settings/Settings.tsx#L1135C1-L1141C7), the fact the call button is now in the header is known and a renaming should happen at some point, there is no mention of it not working or not being supported.

I expected the call button to be missing.

#### What happened instead?

The call button is present in the upper rgight corner.


### Operating system

Linux

### Browser information

Firefox 136.0 (2025-03-04) (64-bit)

### URL for webapp

private server (v1.11.94)

### Application version

Element Version : 1.11.94 Version, crypto : Rust SDK 0.9.0 (5de53c7), Vodozemac 0.8.1

### Homeserver

Synapse v1.123.0

### Will you send logs?

Yes