improve reflection speed/processing

[tzarebczan]

We were backed up on wasabi and it's taking forever to get caught up - 4 seconds per blob. Incoming speeds from other services look fine.

• [x] figure out why it's slow
• [x] run multiple processes in parallel?

[anbsky]

It was slow because of a storage outage. Increased reflection concurrency from 10 to 60 for a good measure.