fixes #13980 - don't merge NIC compute attrs on New Host form

Removes merging of NIC's compute attributes when refreshing interfaces
on compute profile or resource selections on the New Host form. Instead,
overwrite NIC attributes from the profile (as it did before 85e82d0) as
the UI needs refreshing completely on compute profile selection.

Merging of NIC compute attributes with the compute profile is retained
on the host API where it's still valuable for supplying a partial set
of compute attributes.

(cherry picked from commit b299f9c95102be50b1b755376963efed7b3bb6c2)