move dict copy in prep for object-ify flavors

This change is to help split up the patches for object-ifying flavors.
It moves a dict copy of instance_type from the tests to
get_flavor_by_flavor_id().

Change-Id: I0082a56aa637169fd6e1db3aad56877c9f745bc5
Merge "move dict copy in prep for object-ify flavors"