bpf_base_test: fix cgroup2 hardcoded path

the path for cgroup2 was moved to its canonical position by
https://r.android.com/c/1324649/5. Move the hardcoded equivalent to the
same path.

Test: presumit tests pass
Bug: 171770637
Bug: 154548692
Change-Id: I50f7a2385b7de88818ac60b0bcd6b92d711e6e16
(cherry picked from commit 467687c40fbc9e5dfd2eeed0b9221dd2d9bfc060)
1 file changed