net/http: remove arbitrary timeout from TestTransportGCRequest

This test expects a *Request to be garbage collected
within five seconds. Some slow builders take longer.
Drop the arbitrary timeout.

Fixes #56809

Change-Id: I4b5bdce09002a5b52b7b5d0b33e7876d48740bc3
Reviewed-on: https://go-review.googlesource.com/c/go/+/522615
Reviewed-by: Bryan Mills <bcmills@google.com>
Run-TryBot: Damien Neil <dneil@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

src/net/http/clientserver_test.go

@@ -1172,16 +1172,12 @@ func testTransportGCRequest(t *testing.T, mode testMode, body bool) {
 			t.Fatal(err)
 		}
 	})()
-	timeout := time.NewTimer(5 * time.Second)
-	defer timeout.Stop()
 	for {
 		select {
 		case <-didGC:
 			return
-		case <-time.After(100 * time.Millisecond):
+		case <-time.After(1 * time.Millisecond):
 			runtime.GC()
-		case <-timeout.C:
-			t.Fatal("never saw GC of request")
 		}
 	}
 }