Add config that controls if updatable BCP is included in dexpreopt.

For now the config is always set to false (updatable boot jars are
excluded), but this may change in the future.

Bug: 178467404
Test: lunch aosp_cf_x86_64_phone-userdebug && m
Change-Id: I1b45a89748e065a29130efbf8b54dddfae69e48b