configure tuned on jenkins slaves

Just noticed we are not tuning our slaves missing tuned on the systems (at least the one I checked vm0160.workers-phx.ovirt.org )

According to https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html-single/virtualization_tuning_and_optimization_guide/index#chap-Virtualization_Tuning_Optimization_Guide-tuned
we should gain a bit by setting virtual-guest profile within the slaves.