perf: optimize option-type ListArray to Arrow conversion

[aashirvad08]

Description

This PR fixes a performance and memory allocation bottleneck when converting an IndexedOptionArray with ListOffsetArray content to Arrow

The fix avoids redundant data duplication by zeroing the starts/stops of masked elements before to_ListOffsetArray64(False), preventing unnecessary allocations while preserving identical Arrow output.

Results

• ~380× faster execution
• Peak memory reduced from ~5.15 GB to ~5.9 MB
• Byte-identical Arrow output

closes #3646

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.96%. Comparing base (712dac0) to head (72ee935).
⚠️ Report is 57 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

Files with missing lines	Coverage Δ
src/awkward/contents/listarray.py	93.11% <100.00%> (+0.31%)	⬆️

... and 85 files with indirect coverage changes