[sheriff] Disable AccessibilityBridgeTest.OutOfProcessIframe

The test is flaky.

TBR=kmarshall@chromium.org
Bug: 1167266

Change-Id: I1a788509d7bb69439549358f6a8ef651a38526d3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2633841Reviewed-by: Fabrice de Gans-Riberi <fdegans@chromium.org>
Reviewed-by: Yi Gu <yigu@chromium.org>
Commit-Queue: Fabrice de Gans-Riberi <fdegans@chromium.org>
Commit-Queue: Yi Gu <yigu@chromium.org>
Auto-Submit: Fabrice de Gans-Riberi <fdegans@chromium.org>
Cr-Commit-Position: refs/heads/master@{#844200}

fuchsia/engine/browser/accessibility_bridge_browsertest.cc

@@ -616,7 +616,8 @@ IN_PROC_BROWSER_TEST_F(AccessibilityBridgeTest, TreeModificationsAreForwarded) {
   }
 }
 
-IN_PROC_BROWSER_TEST_F(AccessibilityBridgeTest, OutOfProcessIframe) {
+// TODO(crbug.com/1167266): Flaky test.
+IN_PROC_BROWSER_TEST_F(AccessibilityBridgeTest, DISABLED_OutOfProcessIframe) {
   constexpr int64_t kBindingsId = 1234;
 
   // Start a different embedded test server, and load a page on it. The URL for