Mark an overlay related trace integration test as flaky on Win10/Intel

TEST=bots
TBR=sunnyps@chromium.org

Bug: 969117
Change-Id: I2c51dd368e331417d2e5d92fc53dc0eb6a423246
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1643238Reviewed-by: Zhenyao Mo <zmo@chromium.org>
Commit-Queue: Zhenyao Mo <zmo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#666151}

content/test/gpu/gpu_tests/test_expectations/trace_test_expectations.txt

@@ -34,3 +34,4 @@ crbug.com/937545 [ win10 nvidia ] VideoPathTraceTest_DirectComposition_ComplexOv
 # Flaky for unknown reason.
 crbug.com/960007 [ win10 nvidia ] OverlayModeTraceTest_DirectComposition_Nonroot [ RetryOnFailure ]
 crbug.com/965730 [ android qualcomm-adreno-(tm)-418 ] TraceTest_Video_Context_Loss_VP9 [ Skip ]
+crbug.com/969117 [ win10 intel ] OverlayModeTraceTest_DirectComposition_Video_MP4_FourColors_Aspect_4x3 [ RetryOnFailure ]