bpo-38614: Use default join_thread() timeout in tests (GH-17559)

Tests no longer pass a timeout value to join_thread() of
test.support: use the default join_thread() timeout instead
(SHORT_TIMEOUT constant of test.support).
diff --git a/Lib/test/test_queue.py b/Lib/test/test_queue.py
index 46e2a8c..d88e28a 100644
--- a/Lib/test/test_queue.py
+++ b/Lib/test/test_queue.py
@@ -63,7 +63,7 @@
                           block_func)
             return self.result
         finally:
-            support.join_thread(thread, 10) # make sure the thread terminates
+            support.join_thread(thread) # make sure the thread terminates
 
     # Call this instead if block_func is supposed to raise an exception.
     def do_exceptional_blocking_test(self,block_func, block_args, trigger_func,
@@ -79,7 +79,7 @@
                 self.fail("expected exception of kind %r" %
                                  expected_exception_class)
         finally:
-            support.join_thread(thread, 10) # make sure the thread terminates
+            support.join_thread(thread) # make sure the thread terminates
             if not thread.startedEvent.is_set():
                 self.fail("trigger thread ended but event never set")