Mark another TestEvents test as flaky on linux

I don't think anything has changed recently - the test was always flaky, but
only very rarely. Still, it is causing noise in the buildbots.

llvm-svn: 251699

lldb/packages/Python/lldbsuite/test/python_api/event/TestEvents.py

@@ -101,6 +101,7 @@ class EventAPITestCase(TestBase):
         my_thread.join()
 
     @add_test_categories(['pyapi'])
+    @expectedFlakeyLinux("llvm.org/pr23730") # Flaky, fails ~1/100 cases
     def test_wait_for_event(self):
         """Exercise SBListener.WaitForEvent() API."""
         self.build()