net/http: skip Get flakes in TestClientTimeout tests on windows/arm4

net/http: skip Get flakes in TestClientTimeout tests on windows/arm4

There is already a skip in case of a later failure in the same test on
these platforms. Skip the failure if it occurs earlier too.

For #43120.

Change-Id: Id530370caa6a7df8cae593f6fdcb66871b86b125
Reviewed-on: https://go-review.googlesource.com/c/go/+/425096
Run-TryBot: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Bryan Mills <bcmills@google.com>
Reviewed-by: Damien Neil <dneil@google.com>