wifi: use 1.4 ISupplicant object for 1.4 vts tests

This would ensure that 1.4 vts tests are run with
ISupplicant 1.4 support.

Bug: 194979754
Test: atest VtsHalWifiSupplicantV1_4TargetTest
Change-Id: Ifaa3e1bb27f1df350b83fb7a4c05b6251a7c2d10