shuf: optimize numeric output by avoiding write!()

[CrazyRoka]

Profiling revealed that shuf -i spents approximately 45% of execution time in write!(). The write! macro incurs significant overhead due to string formatting logic.

This commit replaces the standard library formatting with a manual integer to string conversion. This avoids heap allocations and locking overhead

[codspeed-hq]

CodSpeed Performance Report

Merging #10048 will improve performance by 40.31%

_{Comparing CrazyRoka:shuf-optimize-printing (5ed3d02) with main (8cf88cd)}

Summary

⚡ 1 improvement
✅ 138 untouched
⏩ 37 skipped¹

Benchmarks breakdown

	Benchmark	BASE	HEAD	Efficiency
⚡	shuf_input_range[1000000]	229.4 ms	163.5 ms	+40.31%

Footnotes

1. 37 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. ↩

[sylvestre]

Merging #10048 will improve performance by 40.31%

Indeed!