Don't send SessionCallbacks for DRY_RUN sessions.

Because DRY_RUN sessions shouldn't have any side effect except to tell
us if verification passed or failed.

Bug: 123753157
Test: atest CtsStagedInstallHostTestCases, with new test added.
Change-Id: Ide42759d80063da76955ef120b21b077197c15e3
1 file changed