Delay dex-to-dex compilation until Optimizing is done.

This fixes a race between inlining in the Optimizing
backend and dex-to-dex quickening where the Optimizing can
read the non-quickened opcode and then the quickened field
index or vtable index and look up the wrong field or method.
Even if we such tearing of the dex instruction does not
happen, the possible reordering of dex-to-dex and Optimizing
compilation makes the final oat file non-deterministic.

Also, remove VerificationResults::RemoveVerifiedMethod() as
we have only the Optimizing backend now and as such it was
dead code and would have interfered with this change.

Bug: 29043547
Bug: 29089975

(cherry picked from commit 492a7fa6)

Change-Id: I1337b772dc69318393845a790e5f6d38aa3de60f