Harden OS_ env vars for VMTP

Harden OS_ env vars for VMTP

VMTP doesn't take into account domain ids and then forces the use of
domain names (detected when verifying ONAP Openlab).

It prints the next warnings and then fails.
2019-09-14 08:43:50,162 WARNING OS_PROJECT_DOMAIN_NAME is missing
2019-09-14 08:43:50,162 WARNING OS_USER_DOMAIN_NAME is missing

Change-Id: I283d86ac0d96071480eefb571da9f2ff92705b08
Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>
(cherry picked from commit d0ce372aeae75c099ade1b742b2bbd826ddb0380)