vts: supplicant: Remove optional service registration

Wifi VendorHAL is optional for STA mode to function.
Tests should be runnable even on devices without VendorHAL.

Bug: 148883970
Test: run vts -m VtsHalWifiSupplicantV1_0Host

Signed-off-by: Oleh Cherpak <oleh.cherpak@globallogic.com>
Change-Id: Ife6e09e41ccfd6c3ccbdc19394175d17986d310d