Pattern for find module was optimized

Regarding answer in https://github.com/ansible/ansible/issues/45048
patterns for find were fixed to be more neat

Change-Id: I65b96138b6f531a8b710c947150564ff13841ae8

tasks/horizon_install_source.yml

@@ -103,11 +103,6 @@
     recurse: no
   register: found_dashboards
 
-# NOTE(noonedeadpunk):
-# patterns made not optimal, as ansible find module doesn't
-# process regexp with repeats, like [0-9]{2,4}.
-# Bug describing this issue:
-# https://github.com/ansible/ansible/issues/45048
 - name: Registering panels
   find:
     paths: |-
@@ -118,7 +113,7 @@
       {%   endfor %}
       {% endfor %}
       {{ dashboard_path }}
-    patterns: "^(_[0-9]{4}_.*.py|_[0-9]{2}_.*.py|.*_policy.json)$"
+    patterns: ["^(_[0-9]{2,4}_.*.py|.*_policy.json)$"]
     file_type: file
     use_regex: yes
   register: found_panels