Change large header size in EndToEndTest.WayTooLongRequestHeaders. Much smaller headers are enough to trigger the behavior this test is exercising. Large headers are causing test timeouts under different scenarios: * TLS + HPACK (b/157248143) * QPACK only on tsan bots on Chromium (b/169262950) PiperOrigin-RevId: 336935923 Change-Id: Idd76963a8e008b459111bd2245d02d446c097fe7