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>

src/net/http/client_test.go

@@ -1272,6 +1272,9 @@ func testClientTimeout(t *testing.T, h2 bool) {
 				t.Logf("timeout before response received")
 				continue
 			}
+			if runtime.GOOS == "windows" && strings.HasPrefix(runtime.GOARCH, "arm") {
+				testenv.SkipFlaky(t, 43120)
+			}
 			t.Fatal(err)
 		}