Added rabbit FIPS flag to FIPS env fle
Added rabbit FIPS flag to FIPS env fle

FIPS requires rabbit to start up in FIPS mode or it will generate an
ed25519 key by default on startup.  The Rabbit FIPS flag sets the
appropriate parameters for this to happen.

Change-Id: I755ef460ca06fdc5bed3a05bba75c63b288b3af8

openstack/tripleo-heat-templates,openstack/tripleo-heat-templates