Pre-allocate data buffer in VarBin::take

[AdamGS]

Saves on many re-allocations of the data buffer in the builder.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.56%. Comparing base (ca28428) to head (2e90821).
⚠️ Report is 6 commits behind head on develop.

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[codspeed-hq]

CodSpeed Performance Report

Merging #4749 will improve performances by 26.69%

_{Comparing adamg/pre-allocate-var-bin-take-data (2e90821) with develop (7730f69)}

Summary

⚡ 1 improvement
✅ 1155 untouched
⏩ 292 skipped¹

Benchmarks breakdown

	Benchmark	BASE	HEAD	Change
⚡	varbin_non_null	156 µs	123.1 µs	+26.69%

Footnotes

1. 292 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[AdamGS]

the benchmark run right now compares against an old base because CI is a bit backed up, I'll re-run it once we get it back on track.

The perf improvement is clear now

[robert3005]

remove this