to be able to do this and see the right object, we need to change the
test case to a private upload directory (defaults to per-vtc working
directory)

to be able to use Lck_AssertHeld()

as of efa1e7d64f8b1a17a02a9fd30df606804ba40a3b

kick the expiry thread

this would lead to DELETEs being always responded to with a 404

This does not make a difference for HTTP1, and as we only use HTTP1
backends, does not many any difference right now.

Uploading files larger than 4GB could lead to an infinite loop and
client requests failing with 423 Locked forever.