Move the aarch64 composes tests/workload to different host

We recently got an unused aarch64 machine from Fedora (sitting in different rack but same cage).

As we're still testing on really old ThunderX (gen1) aarch64 host, we can now move tests to an ampere/emag aarch64 host. Not the fastest/greatest but still better/faster than the old ThunderX

Node should be reinstalled/reconfigured by ansible as kvm host, and ansible inventory modified to use new host (and that will be reflected on https://testing.stream.centos.org tests)