Cannot remove UPF if charm goes into blocked state

[markbeierl]

If the charm goes into a blocked state, for example due to incompatible CPU, the charm cannot be removed cleanly. It goes into error state on cleanup with the following in debug log:

unit-upf-0: 16:32:10 INFO unit.upf/0.juju-log HTTP Request: DELETE https://10.152.183.1/api/v1/namespaces/core/services/upf-external "HTTP/1.1 404 Not Found"
unit-upf-0: 16:32:10 ERROR unit.upf/0.juju-log Uncaught exception while in charm code:
Traceback (most recent call last):
  File "/var/lib/juju/agents/unit-upf-0/charm/venv/lightkube/core/generic_client.py", line 188, in raise_for_status
    resp.raise_for_status()
  File "/var/lib/juju/agents/unit-upf-0/charm/venv/httpx/_models.py", line 759, in raise_for_status
    raise HTTPStatusError(message, request=request, response=self)
httpx.HTTPStatusError: Client error '404 Not Found' for url 'https://10.152.183.1/api/v1/namespaces/core/services/upf-external'
For more information check: https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/404