certmonger: improve orchestration for puppet4

certmonger: improve orchestration for puppet4

The extract-and-trust-ca actually needs /var/lib/certmonger/local/creds
file to be created, which is created when certmonger is started, not
when package is installed.
This patch change the exec dependency to run it only when service is
started.
Also, since the service create the file, let's relax the Exec a little
bit by allowing to retry 5 times after 1s break in case the Exec fails,
for example if service takes more than 5 seconds to create this file.
It will avoid us some race condition in the deployment.

Change-Id: I4cf4a04bddb8f042e8e8f7e1d1b69f846c533e3b