Revert "use dalvik.vm.boot-dex2oat-threads inside microdroid"

This reverts commit eee72d6cb3d9f5c6001192247861b28cb0787827.

REASON: not needed. See the other CL in the same topic.
Bug: 197358423
Test: m
Change-Id: Ice0813ed9e349e37c83b163e2c21f17bb1105013
4 files changed