[Openstack-i18n] [Keystone] String Freeze Exception for https://review.openstack.org/#/c/121246/

A release blocking change[1] is adding a new exception for handling a case where there are multiple SQL configurations in a multi-domain setup. This is a case where the exception makes sense as there are no current exceptions that cover this specific error in enough detail. Bringing it to the attention of this list per the wiki [2]. [1] https://review.openstack.org/#/c/121246/ [2] https://wiki.openstack.org/wiki/StringFreeze — Morgan Fainberg