Make the additional_erl_args change more independent
Make the additional_erl_args change more independent

In I3bf244a70538209773804eb85fae6be035c587f4 we made sure that
we use the additional_erl_args to define parameters. This all
works well but it requires the corresponding THT change
(I567839785a72813a382a00253562894e19eb6715). Let's make it so
that we can merge all the puppet changes without mandating the
THT change at the same time. This makes things easier when backporting.

Tested by deploying a queens environment with this change,
puppet-rabbitmq from master and correctly got a working rabbitmq
cluster. (I.e. we avoided deploying with the corresponding THT change)

Change-Id: I9fa9ba95410ed3994f608beb2c5e1578dc3a7c7a
Related-Bug: #1884922

openstack/puppet-tripleo,openstack/puppet-tripleo,openstack/puppet-tripleo