fix(autoware_string_stamped_overlay_rviz_plugin): clear overlay if message timestamp is old#22

saka1-s wants to merge 2 commits intoautowarefoundation:mainautowarefoundation/autoware_rviz_plugins:mainfrom

saka1-s:fix/clear-overlay-if-oldsaka1-s/autoware_rviz_plugins:fix/clear-overlay-if-oldCopy head branch name to clipboard