Replaced "kolla_external_fqdn_cacert" and "kolla_internal_fqdn_cacert" with
"kolla_admin_openrc_cacert". OS_CACERT is now set to the value of
"kolla_admin_openrc_cacert" in the generated admin-openrc.sh file.

Change-Id: If195d5402579cee9a14b91f63f5fde84eb84cccf
Partially-Implements: blueprint add-ssl-internal-network
Depends-On: https://review.opendev.org/#/c/731344/