Remove cpu_mode option from Libvirt provisioning tests

[Gauravtalreja1]

Problem Statement

cpu_mode option is removed in SAT-22491 and upstream PR theforeman/foreman#9963, causing Libvirt provisioning tests to fail

Solution

Remove cpu_mode option from Libvirt provisioning tests

Dependant PRs:

SatelliteQE/airgun#1486

[Gauravtalreja1]

trigger: test-robottelo
pytest: tests/foreman/{cli,ui}/test_computeresource_libvirt.py -k test_positive_provision_end_to_end
airgun: 1486
provisioning: true
env:
     BROKER_SSH_BACKEND: hussh

[Satellite-QE]

PRT Result

Build Number: 8013
Build Status: UNSTABLE
PRT Comment: pytest tests/foreman/{cli,ui}/test_computeresource_libvirt.py -k test_positive_provision_end_to_end --external-logging --include-onprem-provisioning
Test Result : ========== 29 deselected, 66 warnings, 6 errors in 798.57s (0:13:18) ===========

[Gauravtalreja1]

trigger: test-robottelo
pytest: tests/foreman/{cli,ui}/test_computeresource_libvirt.py -k test_positive_provision_end_to_end
airgun: 1486
provisioning: true
env:
     BROKER_SSH_BACKEND: hussh

[Satellite-QE]

PRT Result

Build Number: 8052
Build Status: UNSTABLE
PRT Comment: pytest tests/foreman/{cli,ui}/test_computeresource_libvirt.py -k test_positive_provision_end_to_end --external-logging --include-onprem-provisioning
Test Result : ==== 2 failed, 4 passed, 29 deselected, 966 warnings in 10867.32s (3:01:07) ====

[Gauravtalreja1]

PRT is expected to fail here for EL9 host due to known issue with SAT-22491