The kolla_enable_letsencrypt variable was undefined, which was causing
overcloud container image build to fail when the variable was not
defined in Kayobe configuration.
The bool filter was missing for kolla_enable_letsencrypt, which was
causing letsencrypt images to be built when kolla_enable_letsencrypt was
set to "false" or "no".
Change-Id: I234b7a0434ba3d533a66b766331fd489078fbcf8
9669462208