Cleanup variable naming by using systemdUnit as a prefix instead of the ambiguous "unit"

[conallob]

No description provided.

[SuperQ]

This appears to have unrelated changes in it.

[conallob]

This appears to have unrelated changes in it.

But it's a clean branch I made this morning. Unless git branched from the branch I was in when I created this branch, instead of master. Let's wrap up #2699 first, then see if this a much smaller delta

[SuperQ]

Unless git branched from the branch I was in when I created this branch

Yes, it does that.

[conallob]

Unless git branched from the branch I was in when I created this branch

Yes, it does that.

Given how easy it makes ignoring code review in favour of running off on your own, I'm surprised it's the default behaviour. Rebased against master now.

[discordianfish]

Now there is only #2699 in here