Add require_root to FakeVehicleHardwareTest.

According to b/329690075, vendor tests need root to use vendor
lib, otherwise atest will cause link error.

Test: atest FakeVehicleHardwareTest on cf_auto
Flag: EXEMPT bug
Bug: 341762230
Merged-In: I6bab19b20e6fe91dbdb2a6526172a5dd1d092ff5
(cherry-picked from commit: f01c7aec)

Change-Id: I6bab19b20e6fe91dbdb2a6526172a5dd1d092ff5