Improve worst case block proof timeout

[Mirko-von-Leipzig]

Currently a block proof is only considered failed after 10 retries, with each retry timing out after 4 minutes. While we should timeout each gRPC/proof attempt, we likely want to bound the overall block in terms of time as well. So retries, attempt time and overall time should all be limited.

Note that this combination means we have a worst case of 40minutes allowed for a proof.

An alternative is to have two separate timeouts. One for each block proof attempt, and one overall one (instead of max retries). We can discuss/do that in a separate PR though, its not really impactful yet.

Originally posted by @Mirko-von-Leipzig in #1725 (comment)

[Mirko-von-Leipzig]

As part of this, I would also ensure that the span tree looks appropriate.