Fix server update attribute test
Fix server update attribute test

This is testing if an attribute not in the update_allowed_keys
results in UpdateReplace. Whilst this is true here, it's using
an attribute that is not a valid resource attribute. The only
valid resource attributes that I know of are:
(Properties, Metadata, UpdatePolicy, DeletionPolicy)

Just want to make sure we are testing the right thing.

Change-Id: Ic84239b0ff3960968293c2c367971f30d091e833

maestro-hybrid-cloud/heat,rh-s/heat,noironetworks/heat,redhat-openstack/heat,dims/heat,srznew/heat,pratikmallya/heat,NeCTAR-RC/heat,cryptickp/heat,openstack/heat,steveb/heat,dragorosson/heat,srznew/heat,gonzolino/heat,jasondunsmore/heat,takeshineshiro/heat,takeshineshiro/heat,cwolferh/heat-scratch,miguelgrinberg/heat,rh-s/heat,miguelgrinberg/heat,cryptickp/heat,ntt-sic/heat,rdo-management/heat,dragorosson/heat,steveb/heat,gonzolino/heat,cwolferh/heat-scratch,dims/heat,pratikmallya/heat,jasondunsmore/heat,noironetworks/heat,openstack/heat,NeCTAR-RC/heat,maestro-hybrid-cloud/heat,pshchelo/heat,redhat-openstack/heat,pshchelo/heat,rdo-management/heat,ntt-sic/heat