Fix the symlink test in AbiTest.

The old hack was fooled by dangling symlinks which, although ugly and
ideally not present, aren't worth forcing everyone to clean up.

Bug: http://b/202226059
Test: treehugger
Change-Id: Iecd79b975820e1a8ea5ff5381667a1cb025ff714
(cherry picked from commit e4aacccf55be1f03c5f65fd6f79f59729cbc948a)