Simplification Hits Ethereum with Optimized Block-Level Access List Update

EIP-7981 simplifies the BAL size constraint by removing CL-coupled constants. The updated formula is `bal_items <= block_gas_limit // 2000`. This change uses the true minimum cost per BAL item, `COLD_SLOAD_COST` (2100), instead of an implicit value. The update creates a buffer to absorb system contracts and withdrawals, making gas allocation more efficient.