Optimise parallelism in compute cells operations by zipping first

[jimmygchen]

Issue Addressed

We're seeing slow KZG performance on fusaka-devnet-0 and looking for optimisations to improve performance.

Zipping the list first then into_par_iter shows a 10% improvement in performance benchmark, i suspect this might be even more material when running on a beacon node.

Before:

blobs_to_data_column_sidecars_20
                        time:   [11.583 ms 12.041 ms 12.534 ms]
Found 5 outliers among 100 measurements (5.00%)

After:

blobs_to_data_column_sidecars_20
                        time:   [10.506 ms 10.724 ms 10.982 ms]
                        change: [-14.925% -10.941% -6.5452%] (p = 0.00 < 0.05)
                        Performance has improved.
Found 6 outliers among 100 measurements (6.00%)

[eserilev]

Nice!