Support Xen PVH in CloudlinuxOS 8/AlmaLinux

[roberto]

Currently I work with Xen PVH in Cloudlinux and CentOS 7 with an optimal performance (https://en.bmstu.wiki/File:XenModes.png). And now I wolud Iike upgrade to CloudlinuxOS 8 but seems Red Hat Enterprise Linux release 8.x and its clones (like CentOS Linux) cant run as Xen PV DomU anymore. Xen PV guest support has been disabled for all 8.x releases So I suggest included Xen PV guest support again at least in AlmaLinux (because CentOS 8 will be discontinued shortly)