Use 9 for max blobs when sizing BlobCache

[siladu]

EIP-7691 increases max blobs to 9 in Prague

Increase memory impact:

(6 * 32 * 3) -> (9 * 32 * 3)
576 blobs -> 864 blobs
73.7MB -> 110.6MB

Part of #7982

[jflo]

Should be sourced from protocol schedule since we can now configure it in the genesis file.

Doing that in another issue/pr is fine.

[siladu]

Should be sourced from protocol schedule since we can now configure it in the genesis file.

@jflo Agree, I've intentionally left that for now as I think it needs some performance analysis/planning otherwise we could create a performance issue via the config.

This is discussed on the parent issue: #7982 which I will reword and re-add to the backlog now that we've done the necessaries for Pectra.

TL;DR - we could size according to the expected max (e.g. 128 blobs) and then hopefully not have to touch this again. Dynamic from config might be OK too, but we should probably cap it.