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
Merge "Fix server update attribute test"