Update environment import command in niri-session

[Zamanhuseyinli]

Since systemctl's import-environment support is now marked as deprecated and therefore gives a warning, I wanted to make such a correction so that the warning screen disappears, but since systemctl does not support import-environment directly anymore, I think it makes more sense to use only dbus or use systemctl in accordance with its new format.

[YaLTeR]

No we are not doing these hacks just to "hide a warning"

[Zamanhuseyinli]

This isn't a hack or anything; it's a technical method for passing necessary variables using xargs.

[Zamanhuseyinli]

I added this for compatibility reasons, not just as a warning.

[noahpolimon]

@YaLTeR i think denying it is just waiting for it to bite you later on when it breaks something. this is no longer a supported method by systemd.

[HigherOrderLogic]

But it still works, no? Also I prefer it over some hacky bash scripts chaining this PR is proposing.

[Zamanhuseyinli]

Yes, it works, and yes, it's more technical than hacky methods in my opinion, that's why I wanted to add that.Instead of unnecessary scripting clutter, you can use simpler methods like these.

[YaLTeR]

i'm happy to wait until it does bite me later