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 <aschoen@redhat.com>

infrastructure-playbooks/lv-teardown.yml

@@ -22,6 +22,7 @@
   - name: include vars of lv_vars.yaml
     include_vars:
       file: lv_vars.yaml
+    failed_when: false
 
   # need to check if lvm2 is installed
   - name: install lvm2