Refactor UUID test

Oslo is removing uuidutils during the icehouse cycle. We had removed
uuidutils.generate_uuid() in https://review.openstack.org/#/c/60643/
It seems the UUID test was not executed, for example, there is no method
called generate_uuid() in common/utils, the Jekins still passed. This
patch move the testcase and remove the test method for generate_uuid.

Change-Id: If4f508129f0b44d63fe77ed1251c0e0737e7e897
Partial-Bug: #1253497
Merge "Refactor UUID test"