Don't need to check whether codePath /oat dir is existed.

The oat directory doesn't always exist, so it will cause
the failure when moving the package by this check. As the
comment on the b/167241596, we don't need this check. We
remove this check.

Bug: 167241596
Test: build pass and boot success
Test: atest CrossUserPackageVisibilityTests
Change-Id: I6ad9b3269a07de53ee6cf07414308acfffec44e7