xci: osa: Use Ansible modules to create ssl certificates

xci: osa: Use Ansible modules to create ssl certificates

Ansible already provides modules to create ssl certificates so we can
use these instead of running the openssl commands directly. Moreover, we
can drop all the tasks which create the ssl directories since there are
being created by the openssl package which also creates the appropriate
symlinks. Finally, there is no need to generate the certificate on
localhost if only the OPNFV host consumes it, so move these steps to
the appropriate playbook.

Change-Id: I0045945c502013be3d76440876e894a44a092690
Signed-off-by: Markos Chandras <mchandras@suse.de>