fix ansible warning about blazar

In Ansible 2.3.0 when statements should not include jinja2 templating
delimiters such as {{ }} or {% %}
this ps fixes it

Change-Id: I33a42eb8184b77e78332caa2a255e0f251fdf9fc

ansible/roles/blazar/tasks/bootstrap.yml

@@ -46,7 +46,7 @@
   changed_when: blazar_host_aggregate | success
   failed_when:
     - blazar_host_aggregate.rc != 0
-    - "{{ 'already' not in blazar_host_aggregate.stderr }}"
+    - blazar_host_aggregate.stderr.find('already') == -1
   run_once: True
   delegate_to: "{{ groups['blazar-api'][0] }}"