Consider removing --disable-notification-server from Windows mozconfigs

On Windows, we use --disable-notification-server.

The reason to do so is that Moz used to disable std::filesystem in libc++.

However, we have been keeping it enabled for a while now (to avoid Win32 API path length limits), so maybe we could enable it.

But before doing so, we should check if this becomes a disk leak risk, and in case update the comment that says why we disable it.