net/http: remove TestTimeoutHandlerAndFlusher due to flakes

net/http: remove TestTimeoutHandlerAndFlusher due to flakes

Removes TestTimeoutHandlerAndFlusher due to flakes on
one of the builders due to timing issues.

Perhaps later, we might need to bring it back when we've
figured out the timing issues.

Fixes #34573.

Change-Id: Ia88d4da31fb228296144dc31f9a4288167fb4a53
Reviewed-on: https://go-review.googlesource.com/c/go/+/197757
Run-TryBot: Emmanuel Odeke <emm.odeke@gmail.com>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>