`Promise.any` will only raise an exception when all of the promises have
rejected (or any promise has resolved); use `Promise.race` instead, where
the first rejecting promise raises.

Signed-off-by: Mark Yen <mark.yen@suse.com>

This reimplements fetchWithRetry to manually watch the progress of the
download, and if there has been no progress in five seconds, abort the
download and retry.  This will hopefully resolve issues in CI where the
whole download times out after ten minutes because the downloads get stuck.

Signed-off-by: Mark Yen <mark.yen@suse.com>