fix: dynamic batch size for tx lookup stage

[onbjerg]

We had some perf regressions on the tx lookup stage. A quick fix was implemented in #3128, but I think this fixes the underlying issue itself.

Essentially, we split the hashing work into batches. The size of these batches were determined by 100_000 / num_cpus. Assume we are on a 16 core machine and the commit threshold of 50_000 was retained.

This gives us:

• Batch size: circa 6k
• Number of batches: circa 8

In other words, we are idling on half of our cores.

I think the reason #3128 alleviated this is because it would give us:

• Batch size: circa 6k
• Number of batches: circa 830

A more reasonable fix is to simply split the amount of available work across all threads evenly, i.e. if your commit threshold is 50k, then the batch size would be 50k / num_cpus.

This also brings the batching logic in line with the sender recovery stage.

[codecov]

Codecov Report

Merging #3134 (a0668d0) into main (39c6b22) will decrease coverage by 0.06%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #3134      +/-   ##
==========================================
- Coverage   70.20%   70.14%   -0.06%     
==========================================
  Files         524      524              
  Lines       69032    69036       +4     
==========================================
- Hits        48462    48427      -35     
- Misses      20570    20609      +39     

Flag	Coverage Δ
integration-tests	16.85% <0.00%> (-0.01%)	⬇️
unit-tests	65.15% <100.00%> (-0.06%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
crates/stages/src/stages/tx_lookup.rs	77.55% <100.00%> (+0.08%)	⬆️

... and 8 files with indirect coverage changes

[gakonst]

will be superseded by https://github.com/paradigmxyz/reth/tree/onbjerg/rm-txlookup-stage

[onbjerg]

@gakonst above branch seems unpopular, although anecdotally it does slow down bodies, but is still faster than having the lookup stage be separate. We can merge this w/o consideration for the above branch

[gakonst]

makes sense