tests: Set the abridged bit in BTM tests

tests: Set the abridged bit in BTM tests

Many of the WNM tests assume that the supplicant will only select a
neighbor that was included in the candidate list. However, without the
abridged bit being set, the supplicant is allowed to also select any BSS
that is not explicitly included in the list.

Prepare for the supplicant handling the abridged bit by setting it in
the tests where relevant.

Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>