Launch Plank on X11

[danirabbit]

What Happened?

We need a dock for the X11 session since the new dock only works with Wayland

Steps to Reproduce

Start X11 session and see there's no dock since 956125b

Expected Behavior

Make sure we launch Plank under X11

OS Version

8.x (Early Access)

Software Version

Latest release (I have run all updates)

Log Output

No response

Hardware Info

No response

[leolost2605]

I think maybe we should do that via a systemd unit or something similar which only launches on X. Because gala probably shouldn't become our makeshift session manager that launches everything 🤷