Let PreRebootVerificationHandler methods take a session object (3/n)

So we don't need getStagedSession() to remap an id to the session
object.

Bug: 167996901
Test: atest StagedInstallTest StagedInstallInternalTest
Change-Id: Iaf7444d0fc924d9e2deda66a6ffbd54d8c32b279
2 files changed