ut failures due to incorrect test cleanup

[bergwolf]

running make test got me following error:

    === RUN   TestCreateMockSandbox
    ERRO[0000] Create new sandbox failed                     error="QEMU path (/tmp/vc-tmp-007004370/hypervisor) does not exist" sandbox=7f49d00d-1995-4156-8c79-5f5ab24ce138 sandboxid=7f49d00d-1995-4156-8c79-5f5ab24ce138 source=virtcontainers subsystem=sandbox
    exit status 1

It is because cleanUp() removes the /tmp/vc-tmp-007004370/hypervisor initially created by TestMain() for all UTs. But we are calling cleanUp() in almost every UT...

[bergwolf]

I'm not sure why I just hit it now. Looking at the code history, the failure seems to exist for a very long time.