Combine reducer and incremental update duration metrics

[joshua-spacetime]

Right now reducer durations and incremental update durations are tracked using two different metrics. We should also have a metric that combines them since a reducer call and an incremental update are logically an atomic unit of execution.

This will give users additional observability into their reducers as they'll be able to see which reducers have more expensive incremental updates.

Note this will be a natural fallout of #1157 since both will be executed as part of the same transaction, but we'll want to make sure to maintain the separated metrics as well.

[Shubham8287]

I think this is the combined metrics that we already have -

SpacetimeDB/crates/core/src/client/message_handlers.rs

Line 185 in 27a7b67

WORKER_METRICS

?

[joshua-spacetime]

@Shubham8287 I'd like to only account for transaction processing time vs the entire time spent on the server. I believe that metric tracks the latter, although correct me if I'm wrong.

[Shubham8287]

@Shubham8287 I'd like to only account for transaction processing time vs the entire time spent on the server. I believe that metric tracks the latter, although correct me if I'm wrong.

You are right, this metric measure entier time spent.