Disable P/CompositorImplBrowserTestRefreshRate.VideoPreference on M x86

Test flakes frequently on M emulator.

BUG=1120813

Change-Id: I481b39088f22e295e31ec5eed155f168e0fbad78
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2373284
Commit-Queue: Theresa  <twellington@chromium.org>
Commit-Queue: Haiyang Pan <hypan@google.com>
Auto-Submit: Theresa  <twellington@chromium.org>
Reviewed-by: Haiyang Pan <hypan@google.com>
Cr-Commit-Position: refs/heads/master@{#801172}

testing/buildbot/filters/android.emulator_m.content_browsertests.filter

@@ -54,3 +54,6 @@
 
 # crbug.com/954217
 -RenderFrameHostImplBrowserTest.VisibilityScrolledOutOfView
+
+# crbug.com/1120813
+-P/CompositorImplBrowserTestRefreshRate.VideoPreference