During block verification, load stash reads from the source blocks on
the device instead of the stashed files. And for interrupted update,
it's pretty common that the source blocks has already been overwritten
by subsequent commands.
In that case the hash printing is mostly useless. Moreover we should have
already printed the hash when the first update failed.
Bug: 80241799
Test: Unit tests pass. No longer prints mismatching stashed source blocks on retry.
Change-Id: I4effe684280b0325199f6cc4b2cc26e91295c2d7