shell: fix exception catching on cleanup
shell: fix exception catching on cleanup

We don't use keystoneclient anymore, I guess someone forgot to change
this. :-) This fixes the error printing on cleanup.

Change-Id: I2552c1d6e839ee5829c53974ee204cb155f97d34

openstack/python-aodhclient,gnocchixyz/python-gnocchiclient,chungg/python-aodhclient,chungg/python-aodhclient,gnocchixyz/python-gnocchiclient,sileht/python-gnocchiclient