Exiting empty beatmap setup should not prompt "save changes"

[RaiLTC]

I sometimes click edit instead of play by accident, having to select no every time kind of gets annoying

[peppy]

This will be easiest fixed via #10314, after which we can remove the isNewBeatmap check which is causing this behaviour to occur.

[LittleEndu]

Don't know if this was a thing last year, but current lazer version (2021.424.0) also automatically selects the Artist field, adding to the annoyance when trying to exit the editor.