Description of problem:
The metrics added in https://github.com/kubevirt/kubevirt/pull/8774

• kubevirt_vmi_cpu_system_seconds
• kubevirt_vmi_cpu_user_seconds
• kubevirt_vmi_cpu_usage_seconds

are counters.
We need to update them and the documentation for them accordingly.

Version-Release number of selected component (if applicable):
4.13.0

How reproducible:
100%

Steps to Reproduce:
1. Create a VM.
2. Run load on the VM CPU
3. Check the CPU metric value

Actual results:

Expected results:

Additional info: