Need to add test cases for FQDN Volume of pr 8244

[YanzhaoLi]

Summary

The #8043 issue has been fixed by the #8244 pr, which has been manually tested well. But I
haven't found a way to add automated test cases for it. This should be done later.

Environment information

vSphere and vCenter Server version

VIC version

VCH configuration

Details

Steps to reproduce

Actual behavior

Expected behavior

Logs

See also

Troubleshooting attempted

• Searched GitHub for existing issues. (Mention any similar issues under "See also", above.)
• Searched the documentation for relevant troubleshooting guidance.
• Searched for a relevant VMware KB article.

[YanzhaoLi]

If we do have a dhcp server in CI environment, our created nfs-server could gain an fqdn from the dhcp server. Thus, we use nslookup to get the fqdn by ip, and then we can test fqdn nfs volume.