webtorrent-desktop: fix .desktop Path entries (#45477)

Fixes the `Path=/opt/webtorrent-desktop` entries [here](https://github.com/webtorrent/webtorrent-desktop/blob/41511c56153b878b0dd39b2adac9525fb66fb35c/static/linux/share/applications/webtorrent-desktop.desktop#L11-L13) -- presently these prevent users from launching the application using the `.desktop` entry.