Fix performance issue in v2 tolist.

[jpivarski]

No description provided.

[codecov]

Codecov Report

Merging #1418 (5e83f11) into main (edfce38) will decrease coverage by 0.05%.
The diff coverage is 43.54%.

Impacted Files	Coverage Δ
src/awkward/_v2/_connect/cuda/__init__.py	0.00% <0.00%> (ø)
src/awkward/_v2/_connect/jax/__init__.py	0.00% <0.00%> (ø)
src/awkward/_v2/contents/indexedarray.py	62.32% <0.00%> (+0.43%)	⬆️
src/awkward/_v2/operations/convert/ak_from_cupy.py	50.00% <0.00%> (+23.33%)	⬆️
src/awkward/_v2/operations/convert/ak_from_jax.py	50.00% <0.00%> (-25.00%)	⬇️
src/awkward/_v2/operations/convert/ak_to_cupy.py	33.33% <0.00%> (+23.95%)	⬆️
src/awkward/_v2/operations/convert/ak_to_jax.py	33.33% <0.00%> (-41.67%)	⬇️
src/awkward/_v2/operations/describe/ak_backend.py	10.00% <0.00%> (-2.50%)	⬇️
src/awkward/_v2/_util.py	75.11% <37.06%> (-8.22%)	⬇️
src/awkward/_v2/contents/numpyarray.py	90.42% <50.00%> (-0.15%)	⬇️
... and 10 more