lv-teardown: fail silently if lv_vars.yml is not found
lv-teardown: fail silently if lv_vars.yml is not found

This allows user to opt out of using lv_vars.yml and load configuration
from other sources.

Signed-off-by: Andrew Schoen <1bb641dc23c3a93cce4eee683bcf4b2bea7903a3@redhat.com>

fgal/ceph-ansible,fgal/ceph-ansible,ceph/ceph-ansible,ceph/ceph-ansible