Squash prometheus counter is always 0

[matthewdarwin]

Squash prometheus counter is always 0. It's been broken for a few releases, I think.

$ curl -s http://localhost:9102/metrics | grep squash
# HELP substreams_total_squash_processes_closed Counter for Total squash processes closed, used for active processes
# TYPE substreams_total_squash_processes_closed counter
substreams_total_squash_processes_closed 0
# HELP substreams_total_squash_processes_launched Counter for Total squash processes launched, used for rate
# TYPE substreams_total_squash_processes_launched counter
substreams_total_squash_processes_launched 0
# HELP substreams_total_squashes_launched Counter for Total squashes launched, used for rate
# TYPE substreams_total_squashes_launched counter
substreams_total_squashes_launched 0

[sduchesneau]

duplicate of #546