Three levels of clean-up is implemented to facilitate different
scenarios:
1. quick clean-up that removes resources created by tempest tests.
This can be used in-between test runs.
2. extensive clean-up that, in addition to 1, also removes test
accounts, project, and the associated network resources. This is
used after charm refresh and identity-ops relation departed where
the previous test accounts becomes obsoletes.
3. full cleanup that, in addition to 1 and 2, deletes the testing
domain, user, and project created through keystone relation. This
is used at the initial stage of keystone relation joins to get
a fresh env.
Change-Id: If172e9dde0e04c53849d7a0b30fc27f62c5bdbd9
b0151aa6ee