Fix flaky connection background establishment test. (#1833)

Author: vbabanin

driver-sync/src/test/functional/com/mongodb/client/AbstractClientSideOperationsTimeoutProseTest.java

@@ -1053,7 +1053,7 @@ public void shouldUseConnectTimeoutMsWhenEstablishingConnectionInBackground() {
         }
 
         List<CommandFailedEvent> commandFailedEvents = commandListener.getCommandFailedEvents("isMaster");
-        assertEquals(1, commandFailedEvents.size());
+        assertFalse(commandFailedEvents.isEmpty());
         assertInstanceOf(MongoOperationTimeoutException.class, commandFailedEvents.get(0).getThrowable());
     }