Telemetry: Disable TabTest:testTabIsAlive on Android due to its failure

Disable TabTest:testTabIsAlive on Android because it fails on FYI bot Android Tests (K N5, user build)(dbg). Re-enable it after the test on Android is fixed. See details in https://crbug.com/463933

BUG=463933

Review URL: https://codereview.chromium.org/971613004

Cr-Commit-Position: refs/heads/master@{#319104}

tools/telemetry/telemetry/core/tab_unittest.py

@@ -164,6 +164,7 @@ class TabTest(tab_test_case.TabTestCase):
     # renderer_thread corresponding to it in the the trace.
     self.assertIs(None, timeline_model.GetRendererThreadFromTabId(third_tab.id))
 
+  @decorators.Disabled('android') # https://crbug.com/463933
   def testTabIsAlive(self):
     self.assertEquals(self._tab.url, 'about:blank')
     self.assertTrue(self._tab.IsAlive())