Disable /cache/dalvik-cache (temporarily?)

When writing to /cache, processes are inheriting their own ownership
permissions instead of the system/metagroup abstraction used in /data,
which makes writing to this dalvik-cache fail.

Go back to using only /data until this is identified and fixed

Change-Id: I9ae19321f158ac86a9c5dd4d2db1268eec278c11