prometheus exporter does not include tier1 or tier2 in the "ready" status

[matthewdarwin]

The prometheus exporter does not include susbtreams tier1 or tier2 in the "ready" status.

Seen on substreams tier2, for example:

# HELP ready readiness of an app. 1 if ready, 0 otherwise
# TYPE ready gauge
ready{app="block-indexer"} 0
ready{app="firehose"} 0
ready{app="merger"} 0
ready{app="relayer"} 0

[matthewdarwin]

Closing in favour of: https://github.com/streamingfast/firehose-core/issues/6