Find requests or jobs insert/retrieve the most data from Redis

This is an exit criteria for &212

We need to understand how data is moving in and out of Redis and why. We could start by looking at which requests and jobs are inserting and retrieving the most data. Where the usage does not make sense we should raise follow up issues to investigate in detail.

The outcome of this issue should be:

1. We can find this data (if we can't, we should create a blocking issue to fix that).
2. We've created issues in &259 for anything we discovered that needs to be fixed or investigated further.