Don't hold install lock while hashing dynamic code files.

This doesn't clash with other installd operations and shouldn't block
them (or be blocked by them).

Bug: 122733719
Bug: 111338677
Bug: 111336847

Test: atest -p services/core/java/com/android/server/pm/dex
Change-Id: Icb79e727ffd904ec23937361ecb3ad3ab29387a1