Disable BookmarksExtensionAPITest.All on all platforms

The test are flaky on win, mac and chromeos.

Bug: 1028272, 1022213
Tbr: rbpotter@chromium.org
Change-Id: I0d233a9fc1236a33880ef8e2bf1114037268e336
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1933409Reviewed-by: Owen Min <zmin@chromium.org>
Commit-Queue: Owen Min <zmin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#718834}

chrome/test/data/webui/bookmarks/bookmarks_browsertest.js

@@ -223,7 +223,7 @@ var BookmarksExtensionAPITest = class extends BookmarksBrowserTest {
   }
 };
 
-TEST_F('BookmarksExtensionAPITest', 'All', function() {
+TEST_F('BookmarksExtensionAPITest', 'DISABLED_All', function() {
   mocha.run();
 });