Stop circref TODO based on RT#82942 from failing after changes in 96577657
Add extra operations to the heavy duty leaktrace scope

Fire all so-far-collected resultsets multiple times
Make Devel::FindRef available on travis

(even though it does not currently work at all on 5.18+)
Smoke 5.16.2 (ensure no leak is triggered) and bump 5.18 bleadcpan