Shorten drastically the timeout of wget (#17736)

By default wget has a timeout of 900 seconds for each of DNS lookup, TCP
connection, and idle time. Shortening it will make the --fast runs more
predictable in duration.

I was hesitating to put an even lower timeout to match better what the
expectation of users might be: I would probably try to restart a
download that was idle for 60 seconds.

But I'm also afraid of triggering too many fast negative.