Remove deadlock/lock contention on Incremental progress update.

Incremental progress is updated separately, and can create deadlock or
simply wait for mLock while session is doing some heavy processing. This
in turn blocks progress update or binder thread, causing long delays for
all other packages.

Bug: 160635296
Test: atest PackageManagerShellCommandTest PackageManagerShellCommandIncrementalTest IncrementalServiceTest PackageManagerServiceTest ChecksumsTest
Change-Id: I6120443a03ec22d1ca672e5a1acf8b3752e1c3ee
Merged-In: I6120443a03ec22d1ca672e5a1acf8b3752e1c3ee