aarch64 builders upgrade

[Kevin Fenzi]

Greetings.

I thought I would let everyone know that I have moved all the buildvm-a64
instances from some older hardware (lenovo emags) to newer hardware
(altra Mt. Snow). This should result in a noticable speed increase
along with allowing us to increase density of vm's per host.

If you notice any issues with buildvm-a64 machines, please file an 
infrastructure ticket: https://pagure.io/fedora-infrastructure

Thanks,

kevin