Remove TestCocoon from Puppet's ci_tester runs

The tool is not used, and caused problems in our
Puppet runs. The URL Puppet tried to reach was unavailable.

Change-Id: I22ae64b9e5dfb4d152913f3bc1ea9e69bfc2b5d3
Reviewed-by: Sergio Ahumada <sergio.ahumada@digia.com>