fix: don't enable foldhash by default

[DaniPopes]

Fixes #767

[hai-rise]

@DaniPopes @mattsse I did a naive dep bump for pevm today, it was consistently red with up to 35% regression.
https://github.com/risechain/pevm/pull/386/files

10-35% regression on a casual alloy-primitives bump is very scary, and I don't think most library users have rigid benchmarks to catch it. I'd suggest either:

• Tell people loud and clear to enable map-foldhash for performance-critical usage, or
• Revert this and ask users affected by Default hasher foldhash queries the time #767 to use something like no-default?