Disable flaky test testSiteExceptionCookiesBlocked

The test has been flaky recently. Please see bug for details.

TBR=andypaicu@chromium.org

Bug: 1090274
Change-Id: If92d3983d0bfb2402bfdfdc27fe5d92e30041d44
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2230759Reviewed-by: Yi Gu <yigu@chromium.org>
Commit-Queue: Yi Gu <yigu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#775100}

chrome/android/javatests/src/org/chromium/chrome/browser/site_settings/SiteSettingsTest.java

@@ -468,6 +468,7 @@ public class SiteSettingsTest {
      * Blocks specific sites from setting cookies and ensures that no cookies can be set.
      */
     @Test
+    @DisabledTest(message = "crbug.com/1090274")
     @SmallTest
     @Feature({"Preferences"})
     // Todo(eokoyomon) figure out how to set and test third party cookie setting in this test