Fix log mount of nginx-proxy

access and error logs of nginx-proxy point to `/dev/stdout` and `/dev/stderr`.
```
l /opt/easyengine/services/nginx-proxy/logs/
total 8.0K
drwxr-xr-x 2 root root 4.0K Jan 2 03:58 .
drwxr-xr-x 3 root root 4.0K Jan 2 03:58 ..
lrwxrwxrwx 1 root root 11 Nov 7 00:27 access.log -> /dev/stdout
lrwxrwxrwx 1 root root 11 Nov 7 00:27 error.log -> /dev/stderr
```

We need to mount them correctly.