integration: bump timeout for good path

When waiting for a watch result, we expect the good path to complete
quickly here so we don't need to time out so aggressively. (Failure
noted in #1600)

integration/v2_http_kv_test.go

@@ -847,7 +847,7 @@ func TestV2WatchWithIndex(t *testing.T) {
 
 	select {
 	case <-c:
-	case <-time.After(time.Millisecond):
+	case <-time.After(time.Second):
 		t.Fatal("cannot get watch result")
 	}