since the FQPN already appears in the message this generates, just go with the name of the thing being deprecated in the namespace it is being deprecated in

refs #7653


git-svn-id: svn://svn.twistedmatrix.com/svn/Twisted/branches/deprecate-jelly-instance-support-7653@43240 bbbe8e31-12d6-0310-92fd-ac37d47ddeeb