Disable Dexpreopt for generic_arm5

Bug 5267392

After coming across another place where I would have to use
package.apk.unaligned, I decided maybe it is best to just
disable dexpreopt as was previously suggested.

Use package.apks in the CTS Makefile task.

Change-Id: Iec839a72f4b53441337523b8a9cccda657eec8e8