Skydive: fix facts retrieved two times

Facts are retrieved a second time if skydive is enabled.
This patch fix it.

Change-Id: I4fc15daf59b093e4b29ff9f1fc703c8b2a65b238

ansible/site.yml

@@ -660,6 +660,7 @@
         when: enable_zun | bool }
 
 - name: Apply role skydive
+  gather_facts: false
   hosts:
     - skydive-agent
     - skydive-analyzer
@@ -668,4 +669,3 @@
     - { role: skydive,
         tags: skydive,
         when: enable_skydive | bool }
-