Description of problem:

given a running VM with two virtual NICs based on port-mirroring vNIC profile, 
its impossible to unplug them ending in this error in the UI:

Error while executing action Edit VM Interface properties: General Exception

VDSM log shows the following traceback:

Traceback (most recent call last):
  File "/usr/lib/python3.6/site-packages/vdsm/common/api.py", line 124, in method
    ret = func(*args, **kwargs)
  File "/usr/lib/python3.6/site-packages/vdsm/API.py", line 301, in destroy
    res = self.vm.destroy(gracefulAttempts)
  File "/usr/lib/python3.6/site-packages/vdsm/virt/vm.py", line 5169, in destroy
    result = self.doDestroy(gracefulAttempts, reason)
  File "/usr/lib/python3.6/site-packages/vdsm/virt/vm.py", line 5188, in doDestroy
    return self.releaseVm(gracefulAttempts)
  File "/usr/lib/python3.6/site-packages/vdsm/virt/vm.py", line 5070, in releaseVm
    nic.name)
  File "/usr/lib/python3.6/site-packages/vdsm/common/supervdsm.py", line 56, in __call__
    return callMethod()
  File "/usr/lib/python3.6/site-packages/vdsm/common/supervdsm.py", line 54, in <lambda>
    **kwargs)
  File "<string>", line 2, in unsetPortMirroring
  File "/usr/lib64/python3.6/multiprocessing/managers.py", line 772, in _callmethod
    raise convert_to_error(kind, result)
vdsm.network.tc._parser.TCParseError: Found 0, expected ('qdisc', 'class', 'filter')


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

vdsm-4.40.60.3-1.el8ev.x86_64


How reproducible:

always 

Steps to Reproduce:
1. create a network
2. attach network to one of the hosts.
3. start the VM.
4. create a vNIC profile based on port-mirroring for network.
5. create 2 VNICs with the port-mirroring vNIC profile for that VM.
6. try to unplug any of those 2 vNICs.
7. UI gives error: Error while executing action Edit VM Interface properties: General Exception

Actual results:

unable to unplug a vNIC based on port-mirroring.


Expected results:

vNIC is unplugged successfully.