Disable flaky android test

testExitPersistentFullscreenAllowsManualFullscreen is flaky:
https://analysis.chromium.org/p/chromium/flake-portal/flakes/occurrences?key=ag9zfmZpbmRpdC1mb3ItbWVymwELEgVGbGFrZSKPAWNocm9taXVtQGNocm9tZV9wdWJsaWNfdGVzdF9hcGtAb3JnLmNocm9taXVtLmNocm9tZS5icm93c2VyLmZ1bGxzY3JlZW4uRnVsbHNjcmVlbk1hbmFnZXJUZXN0I3Rlc3RFeGl0UGVyc2lzdGVudEZ1bGxzY3JlZW5BbGxvd3NNYW51YWxGdWxsc2NyZWVuDA

TBR=tedchoc@chromium.org

Bug: 1046749
Change-Id: If5d65f76fc9cd2351c24a47dab06843b4b9bd16e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2028656Reviewed-by: Yi Gu <yigu@chromium.org>
Commit-Queue: Yi Gu <yigu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#736546}

chrome/android/javatests/src/org/chromium/chrome/browser/fullscreen/FullscreenManagerTest.java

@@ -198,6 +198,7 @@ public class FullscreenManagerTest {
     @Test
     @LargeTest
     @Feature({"Fullscreen"})
+    @DisabledTest(message = "crbug.com/1046749")
     public void testExitPersistentFullscreenAllowsManualFullscreen() {
         FullscreenManagerTestUtils.disableBrowserOverrides();
         mActivityTestRule.startMainActivityWithURL(LONG_FULLSCREEN_API_HTML_TEST_PAGE);