Revert^2 "Avoid crash when ANDROID_DATA is not writeable."

This reverts commit c702e343.

Fix the new test when running as root. Instead of relying on
directory permissions (which are ignored for root), create
a dummy file "dalvik-cache" to prevent the creation of the
directory "dalvik-cache/<isa>".

Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing
Test: Pixel 2 XL boots.
Test: m test-art-target-gtest
Bug: 112848347
Bug: 112827048
Change-Id: I0fad66c876c5dd062a38aacc15cdd21c374cc96f