Fix testcase with ttl value
Fix testcase with ttl value

- Fix a testcase with ttl below 0
- Add a new testcase with random ttl without None type,
negative value and zero value.

Change-Id: Ibc5f02daa077ae2b089e9ec4a5c78dce801be1c9
Co-authored-By: Dai Dang Van <e73ee691e4aa4bc4b51b1457846b1d6a69cf396f@vn.fujitsu.com>

openstack/designate,openstack/designate,openstack/designate