Use prebuilts of the ART Module by default in SC branches.

This means prebuilts located in
/vendor/unbundled_google/modules/ArtGooglePrebuilt and
/prebuilts/module_sdk/art are used instead of sources in /art,
/libcore, and /libnativehelper.

Sanitizer and coverage builds builds are excluded, as are builds using
the products art_module_*, armv8, arm_krait, and others in
device/generic/art.

To keep using ART and libcore sources in local builds, set
SOONG_CONFIG_art_module_source_build=true. See art/build/README.md for
further info.

Cherry-picked from http://ag/15234812.

Merged-in set to https://r.android.com/1801147 to avoid merging into
master and *-plus-aosp branches, where we want to enable prebuilts
separately.

Test: build & boot on Cuttlefish
Bug: 200554575
Change-Id: Id6800fe3564149e6c555b5f68a41b01e9c7dff3f
Merged-In: I50187408a01e0c6f5ecea12fe3a423e1c5d93612