Reduce the frequency of Zebra performance logs

[teor2345]

Motivation

As part of #4747, we added some info-level performance logs to Zebra.

But performance is good enough now, so we can reduce the frequency of those logs.

Tasks

We could downgrade all the logs to debug level, but it might still be useful to log them for very long tasks.

For example:

• the state can take up to a minute to commit a block, so we want to log that at trace or debug level
• rebuilding non-finalized note commitment trees can take 1-2 minutes, so we could log that at info level
• blocks timeout after 10 minutes, so we might want to log a warning before 10 minutes

The performance logging is implemented in:
https://github.com/ZcashFoundation/zebra/blob/main/zebra-chain/src/diagnostic.rs

[teor2345]

Fixed by #4997.