Bug 1985670

Description of problem
----------------------

Creation of VirtualMachines is failing due an error with cgroups in virt-launcher Pod:

> server error. command SyncVMI failed: "LibvirtError(Code=38, Domain=54, Message='Failed to create v1 controller cpu for group: Read-only file system')"

Version
-------

OCP: v4.9.0-0.nightly-2021-07-24-064622
RHCOS: v49.84.202107220219-0
CNV: http://cnv-version-explorer.apps.cnv.engineering.redhat.com/BundleDetails?ver=v4.9.0-57

How reproducible
----------------

100%

Steps to Reproduce
------------------

Create a basic VM:

> ---
> kind: VirtualMachine
> apiVersion: kubevirt.io/v1
> metadata:
>   name: cirros
> spec:
>   template:
>     spec:
>       domain:
>         cpu:
>           cores: 1
>         devices:
>           disks:
>             - name: rootdisk
>               disk:
>                 bus: virtio
>         resources:
>           requests:
>             memory: '128Mi'
>       volumes:
>         - name: rootdisk
>           dataVolume:
>             name: cirros-rootdisk
>   running: true
>   dataVolumeTemplates:
>     - metadata:
>         name: cirros-rootdisk
>       spec:
>         source:
>           http:
>             url: http://cnv-qe-server.rhevdev.lab.eng.rdu2.redhat.com/files/cnv-tests/cirros-images/cirros-0.5.1-x86_64-disk.img
>         pvc:
>           accessModes:
>             - ReadWriteOnce
>           resources:
>             requests:
>               storage: '150Mi'

Actual results
--------------

The VirtualMachineInstance stays in Scheduled Phase because the virt-launcher Pod is facing issues with cgroups:

> {"component":"virt-launcher","level":"error","msg":"Failed to create v1 controller cpu for group: Read-only file system","pos":"virCgroupV1MakeGroup:675","subcomponent":"libvirt","thread":"34","timestamp":"2021-07-24T19:34:56.099000Z"}
> {"component":"virt-launcher","kind":"","level":"error","msg":"Failed to start VirtualMachineInstance with flags 0.","name":"cirros","namespace":"openshift-cnv","pos":"manager.go:827","reason":"virError(Code=38, Domain=54, Message='Failed to create v1 controller cpu for group: Read-only file system')","timestamp":"2021-07-24T19:34:56.305333Z","uid":"d6b381b1-367b-4882-a6a4-9fc1b84745b5"}
> {"component":"virt-launcher","kind":"","level":"error","msg":"Failed to sync vmi","name":"cirros","namespace":"openshift-cnv","pos":"server.go:184","reason":"virError(Code=38, Domain=54, Message='Failed to create v1 controller cpu for group: Read-only file system')","timestamp":"2021-07-24T19:34:56.305505Z","uid":"d6b381b1-367b-4882-a6a4-9fc1b84745b5"}

Expected results
----------------

The VirtualMachine should start properly.