Restore the test for bionic being in an APEX.

This was removed in
https://android-review.googlesource.com/c/platform/build/soong/+/950885
because it appeared that bionic was always in an APEX, but apparently the
ART host tests have bionic outside of an APEX.

Test: art/test/testrunner/run_build_test_target.py -j50 art-linux-bionic-x64
Change-Id: I0b99462e8636da53c87f9250093689aaaf9ea695