Disable flaky WebXrVrOpenXrBrowserTest.TestSessionEnded test

Bug: 1115721
Change-Id: I2293535744d9f7894865bd32b9ed9fb4a84a33f9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2353551Reviewed-by: Brian Sheedy <bsheedy@chromium.org>
Commit-Queue: Yuly Novikov <ynovikov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#797471}

chrome/browser/vr/webxr_vr_transition_browser_test.cc

@@ -127,7 +127,7 @@ void TestWebXRSessionEndWhenEventTriggered(
   t->EndTest();
 }
 
-IN_PROC_BROWSER_TEST_F(WebXrVrOpenXrBrowserTest, TestSessionEnded) {
+IN_PROC_BROWSER_TEST_F(WebXrVrOpenXrBrowserTest, DISABLED_TestSessionEnded) {
   TestWebXRSessionEndWhenEventTriggered(
       this, device_test::mojom::EventType::kSessionLost);
 }