Tests: fix time.sleep(0) # yield. Reduce sleep related log messages.

Reduce the incidence of:
20:04:23,606 unexpected time.sleep() result - slept for 2.187967e-03s instead of ~6.837845e-04s!

Change-Id: Ic576fda7f75e571c9019111588a6a936ee2cf5c2
Signed-off-by: Paul Vinciguerra <pvinci@vinciconsulting.com>
diff --git a/test/vpp_papi_provider.py b/test/vpp_papi_provider.py
index 37f63c0..fca57c3 100644
--- a/test/vpp_papi_provider.py
+++ b/test/vpp_papi_provider.py
@@ -303,7 +303,7 @@
                 self.test_class.logger.debug("Returning event %s:%s" %
                                              (name, e))
                 return e
-            time.sleep(0)  # yield
+            self.test_class.sleep(0)  # yield
         raise Exception("Event did not occur within timeout")
 
     def __call__(self, name, event):