Add failing multi-window tests to known-failures.

Since the tests were added in O and their failing cause is hard to
reproduce and they are blocking release I'm adding them to
cts-known-failures to unblock the release and have more time for
investigation.

Bug: 37482372, 38177396
Test: Not needed.

Change-Id: Ib978c98151c9ff6c82b798e55b3c29c46a2d7ffe
1 file changed