The current testing setup only supports running Kata on top of an Ubuntu
host. This adds Mariner to the matrix of testable hosts for k8s
tests, with Cloud Hypervisor as a VMM.
As preparation for the upcoming PR that will change only the actual test
code (rather than workflow YAMLs), this also introduces a new file
`setup.sh` that will be used to set host-specific parameters at test
run-time.
Fixes: #6961
Signed-off-by: Aurélien Bombo <abombo@microsoft.com>