supplicant(vts): Stop adding empty instance for vendor HAL

We don't need to test supplicant in the presence of vendor HAL & without
it. For a given device, this behavior is fixed.

Bug: 161951052
Test: atest VtsHalWifiSupplicantV1_1TargetTest
Merged-In: I71097c3afef1765ca514abf2c350c423e3999020
Change-Id: I71097c3afef1765ca514abf2c350c423e3999020
(cherry picked from commit 984b6e06)