[test] Temporarily disable TestNSNotificationQueue pending rdar://31106944 (#921)

* [test] Temporarily disable TestNSNotificationQueue pending SR-4280.

These tests are failing intermittently in CI.
diff --git a/TestFoundation/TestNSNotificationQueue.swift b/TestFoundation/TestNSNotificationQueue.swift
index 30a6645..2cea068 100644
--- a/TestFoundation/TestNSNotificationQueue.swift
+++ b/TestFoundation/TestNSNotificationQueue.swift
@@ -19,6 +19,9 @@
 class TestNSNotificationQueue : XCTestCase {
     static var allTests : [(String, (TestNSNotificationQueue) -> () throws -> Void)] {
         return [
+/*
+FIXME SR-4280 timeouts in TestNSNotificationQueue tests
+
             ("test_defaultQueue", test_defaultQueue),
             ("test_postNowToDefaultQueueWithoutCoalescing", test_postNowToDefaultQueueWithoutCoalescing),
             ("test_postNowToDefaultQueueWithCoalescing", test_postNowToDefaultQueueWithCoalescing),
@@ -29,6 +32,7 @@
             ("test_postAsapToDefaultQueueWithCoalescingOnNameAndSender", test_postAsapToDefaultQueueWithCoalescingOnNameAndSender),
             ("test_postAsapToDefaultQueueWithCoalescingOnNameOrSender", test_postAsapToDefaultQueueWithCoalescingOnNameOrSender),
             ("test_postIdleToDefaultQueue", test_postIdleToDefaultQueue),
+*/
         ]
     }