Only load Kzg in tests if necessary and only load it once

[jimmygchen]

Issue Addressed

Loading trusted setup file and instantiating the Kzg instance is very expensive (>80% of test time for most tests), and we're doing this quite a lot of times in tests even when we don't need them (e.g. pre-deneb tests), and in some cases they're loaded twice when mock_execution_layer is used.

This PR improves this by loading Kzg trusted setup only once at most, if necessary.

Some numbers when I run beacon chain tests locally:

• unstable branch 180s (~17m on CI)
• unstable + fix (current branch): 173s
• das branch: 990s (>55m on CI)
• das branch with this fix: 269s

The difference isn't significant on unstable, so it looks like Kzg initialisation time has increased quite significantly due the changes in the das version - there's probably more optimisation that can be done on c-kzg but we should probably avoid loading it multiple times in a single test anyway, as we run each of these beacon chain tests once per fork.

Test command used:

env FORK_NAME=deneb cargo nextest run --release --features "fork_from_env,slasher/lmdb,portable" -p beacon_chain

[jimmygchen]

This only works in the beacon-chain-tests crate as the client crate needs to be updated to but I'm not sure if this is a good idea. Will investigate a bit more.

[pawanjay176]

LGTM. Thanks for running the numbers. I'm hoping the das branch in ckzg still has room for optimisations

[realbigsean]

@Mergifyio queue

[mergify]

queue

✅ The pull request has been merged automatically

The pull request has been merged automatically at 7e49f82