Add select_unpredictable hint to search_sorted

[AdamGS]

Summary

Seems to be the main difference between the impl we have and std, docs - https://doc.rust-lang.org/std/hint/fn.select_unpredictable.html

Doesn't seem to make a difference in our benchmarks, probably worth further investigation.

[codspeed-hq]

Merging this PR will degrade performance by 10.6%

⚠️ Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

❌ 1 regressed benchmark
✅ 1274 untouched benchmarks

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Simulation	bitwise_not_vortex_buffer_mut[128]	246.1 ns	275.3 ns	-10.6%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

---

_{Comparing adamg/search-with-std-diff (d8d4277) with develop (81046d7)}

[robert3005]

those hints used to be not available outside of std, glad this changed?