We've introduced couple of new ENV vars that we define in
openstack-ansible.rc file. While they're working properly, we still don't
want them to be used during bootstrap process, as in case of
bootstrap failure somewhere in the middle of execution, like before
our plugins collection being installed, next bootstrap re-runs will fail
with smth like `Invalid play strategy specified: openstack.osa.linear`
In order to fix this we set default values for ANSIBLE_TRANSPORT and
ANSIBLE_STRATEGY that we clean out after bootstrap is completed.
Change-Id: Id34fb425c76bef7615bcbf1334d7a84ac6422fa8
b6cf0973c6