Handle prop not supported correctly.

getPropConfigs() will return error when the property is not supported
instead of returning an empty array. Also make sure GTEST_SKIP is called
directly in the test function, not the helper function since it
will only abort the current function.

Test: atest VtsHalAutomotiveVehicle_TargetTest
Bug: 301577794
Change-Id: I99e2cb8bd00430fe9668e8a911a60bbfe97bc4e0