Fully populate state fields in `randomize_state`

[jtraglia]

Related to:

• https://github.com/ethereum/consensus-specs/pull/4531#issuecomment-3224899640

If I comment out this line in Teku, the current spec tests will not catch it:

• https://github.com/Consensys/teku/blob/764d29eb5dc12aa13d47ecc4659f611ef43f169b/ethereum/spec/src/main/java/tech/pegasys/teku/spec/logic/versions/fulu/forktransition/FuluStateUpgrade.java#L80

The same idea probably applies to other fields too, and other forks.

[victorhugogomezjuare]

Confirmet 🤝🏻

[richardgreg]

Hi @jtraglia, I have reasonable experience debugging Ethereum layer specs and I'd like to take up this task