Connection interruptions during Bag generation can cause partial bags to be stored. #8604
Description
What steps does it take to reproduce the issue? A bug in how threading is done in the DuraCloud and Google archiver classes does not cleanly handle cases where connections are interrupted, potentially resulting in partial Bags and incorrect success status. (general issue as well as for #8603). This PR changes the thread management to always report success/failure correctly and attempt to remove partial Bags that may have been sent to the archival system.