Move validate_requests fn into validate version specific fields for ethereum engine validator

[mattsse]

Describe the feature

ref #14932

after we transitioned the engine api to operate on the entire executiondata we stopped calling
https://github.com/paradigmxyz/reth/blob/main/crates/engine/primitives/src/lib.rs#L140-L140

so we can remove this function and move this to the ethereum specific impl instead

https://github.com/paradigmxyz/reth/blob/main/crates/ethereum/node/src/engine.rs#L54-L54

Additional context

No response