Android: disables DiagnosticsModelTest.RunAll

This test is timing out on android
(it eventually runs very close to the 120s timeout and passes, so it looks like the
flakyness is more about the size than the test itself).

BUG=256259
TBR=cpu@chromium.org
NOTRY=TRUE

Review URL: https://chromiumcodereview.appspot.com/18344007

git-svn-id: http://src.chromium.org/svn/trunk/src/build@209439 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

android/pylib/gtest/filter/unit_tests_disabled

@@ -117,5 +117,8 @@ ManifestTest.RestrictedKeys
 # crbug.com/152599
 SyncSearchEngineDataTypeControllerTest.*
 
+# crbug.com/256259
+DiagnosticsModelTest.RunAll
+
 # Death tests are not supported with apks.
 *DeathTest*