Revert "DO NOT MERGE: Use prebuilts of the ART Module by default (reland 2). am: f68bd2db"
This reverts commit 29502219.
Reason for revert: Follow AOSP for prebuilts in the -plus-aosp branch, i.e. disable them.
Change-Id: I615c644229fbb55a60633c3cc1aba2497674c0b0