systemd integration for Sway is cool, but introduces a lot of
unexpected problems, such as race conditions. So switch back to classic
config-based systemd for autostarting services until all major problems
with systemd integration (sway-systemd) will resolved
This is also removes the ability to substitute system-wide Waybar config
with our own, because Waybar's systemd unit file doesn't provide
such functional. Default Waybar config is now placed in ~/.config/waybar/
