`group_vars/matrix_servers` was correctly populating `matrix_static_files_file_matrix_client_property_org_matrix_msc4143_rtc_foci_auto` with a list, but:

- the defaults for these variables were hinting that hashmaps are necessary

- merging of `_auto` and `_custom` was done as if for hashmaps, not lists

As a result, `/.well-known/matrix/client` looked like this:

```json
{
	"org.matrix.msc4143.rtc_foci": {
		"livekit_service_url": "https://matrix.example.com/livekit-jwt-service",
		"type": "livekit"
	}
}
```

.. instead of what's expected as per MSC4143 (https://github.com/matrix-org/matrix-spec-proposals/pull/4143):

```json
{
	"org.matrix.msc4143.rtc_foci": [
		{
			"livekit_service_url": "https://matrix.example.com/livekit-jwt-service",
			"type": "livekit"
		}
	]
}
```

Regardless of our incorrectly formatted `org.matrix.msc4143.rtc_foci`
configuration in `/.well-known/matrix/client`, Element Web still seemed
to be able to discover LiveKit JWT Service (and by extension, LiveKit Server) correctly,
even without this fix.