performance: Augment existing Indexer/Conduit metrics & logs

[Will Winder]

Make sure the metrics and logs available from Conduit are sufficient for measuring performance.

At a minimum, Conduit needs:

• the total transaction count per block added to the log.
• the # of transactions per type (axfer, pay, app call..)
• the time it took to ingest a block.

Some of this is already available in Indexer.

(out of scope) the idea is that we will use some tool/script to analyze the logs. This is separate from the Prometheus data (general system performance), which uses the metrics endpoint (which reports averages).

[Will Winder]

AFAIK this is out of date.