Refs #12361. Always return true adding a writer

Signed-off-by: Ricardo González Moreno <ricardo@richiware.dev>

src/cpp/rtps/writer/LivelinessManager.cpp

@@ -65,7 +65,7 @@ bool LivelinessManager::add_writer(
     if (!calculate_next())
     {
         timer_.cancel_timer();
-        return false;
+        return true;
     }
 
     // Some times the interval could be negative if a writer expired during the call to this function