Remove the redundant codes
Remove the redundant codes

DeleteInstance action inherits from tables.DeleteAction,
the tables.DeleteAction has already define some attributes.
So this patch remove the repeated attributes.

Change-Id: I7cab3cf609b75e483d5507af113501aa957436c5

openstack/freezer-web-ui,openstack/freezer-web-ui,openstack/freezer-web-ui,openstack/freezer-web-ui