Add `puma_killer_terminations_total` Puma metric
Problem to solve
Currently, part of metrics that are provided by Unicorn, are produced by mtail
.
We need to add metrics that replicate all of Unicorn.
The last missing is puma_killer_terminations_total
that keeps tracks number of worker
restarts.
Proposal
Add puma_killer_terminations_total
by hoking on Puma master to event of terminating
the worker.