Tests are run with proper namespace configs by their locations

Tests in /data/[nativetest|benchmarktest] run with namespace config for
system and tests in /data/[nativetest|benchmarktest]/vendor run with
namespace config for vendor.

They no longer run in the 'test' namespace config which didn't impose
any restriction for libraries.

Bug: 67028906
Test: sailfish/marlin builds and boots
Test: no VTS regression on system.img from GSI + vendor.img from
marlin/sailfish
Test: VtsKernelLibcutilsTest successful in above config

Merged-In: I28cdef960d087565c8a22dca0e9a154fb1c3bb94
Change-Id: I28cdef960d087565c8a22dca0e9a154fb1c3bb94
(cherry picked from commit 326b783a)