CI: performance: machine hyperv windows rootless is getting slower

[edsantiago]

It used to take 40 minutes. End of June, around the time of (and possibly due to) #22922 , yay, down to 30 minutes. Since then, ever so slowly, it has been creeping back up. It is now at 37 minutes.

See graph (scroll down, look at orange line).

[Luap99]

Well I think a large part is that we keep adding tests, a test that does a machine init seems to take at least 20s+, and if we start it is is even worse... just look at some test timings

We need things like #23769 to more effectively make use of machines and not create/start so many of them
cc @baude