feat(cargo-codspeed): build all benches in a single cargo build

[adriencaccia]

As pointed out by @Boshen in oxc-project/oxc#2343, we can build all the benches in a single command.

[codspeed-hq]

CodSpeed Performance Report

Merging #34 will improve performances by 14.2%

_{Comparing feat/single-build (69c8309) with main (fc75139)}

Summary

⚡ 3 improvements
✅ 54 untouched benchmarks

Benchmarks breakdown

	Benchmark	main	feat/single-build	Change
⚡	Auto	223.3 ns	195.6 ns	+14.2%
⚡	Linear	223.3 ns	195.6 ns	+14.2%
⚡	Flat	728.3 ns	700.6 ns	+3.97%

[adriencaccia]

@art049 I made the changes, let me know if it's okay to merge. I don't really know what to make of the performance improvements of the criterion sampling modes benchmarks.

[art049]

LGTM, @adriencaccia; those benches are relying on sleep. Thus we end up with syscall variance.