iotests/stream-error-on-reset: New test

Test the following scenario:
- Simple stream block in two-layer backing chain (base and top)
- The job is drained via blk_drain(), then an error occurs while the job
  settles the ongoing request
- And so the job completes while in blk_drain()

This was reported as a segfault, but is fixed by "block-backend: prevent
dangling BDS pointers across aio_poll()".

Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=2036178


Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20220111153613.25453-3-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>