[2165618] Overhead of management layer in virt-launcher is not calculated accurately

Description of problem:
Kubevirt computes [1] the estimation of total memory needed for the domain to operate properly. This includes the memory needed for the guest and memory for Qemu and OS overhead.

When running IO intensive workloads, the memory consumption by the management layer (e.g. libvirt, QEMU, and other processes in the compute container) is larger than calculated. The difference between the expected and actual consumption is between 700M and 1.3G approximately.

[1] https://github.com/kubevirt/kubevirt/blob/v0.59.0-alpha.2/pkg/virt-controller/services/renderresources.go#L272

Version-Release number of selected component (if applicable):
4.10.1

How reproducible:
100%

Steps to Reproduce:
1. create a VM with either local or ceph disks (Manifests are attached)
2. create xfs filesystem
3. mount the disks
4. run vdbench test as per example (via "vdbench -f test_file")

Actual results:
Memory used by the virt-launcher pod is as or below what's calculated

Expected results:
The difference between the expected and actual consumption is between 700M and 1.3G approximately.

Additional info:
VM Manifest attached