Rm openstack-install for lf-infra-pre-build

lf-infra-pre-build is able to manage openstack client installs
so remove the openstack-install script. No need to release note since
no project should be using openstack-cron yet as in it's current
state is incomplete.

Change-Id: Ic6ee5ae0e5815d2730b3fa6154fd8e6d5b096844
Signed-off-by: Thanh Ha <thanh.ha@linuxfoundation.org>