BufferMut::zeroed_aligned stores actually allocated length instead of passed length

[robert3005]

If length * size_of::<T> overflows the length of the buffer is wrong

[codspeed-hq]

Merging this PR will improve performance by 18.1%

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⚠️ Different runtime environments detected

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⚡ 4 improved benchmarks
✅ 1217 untouched benchmarks

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
⚡	Simulation	chunked_varbinview_canonical_into[(1000, 10)]	198 µs	162 µs	+22.24%
⚡	Simulation	chunked_varbinview_into_canonical[(100, 100)]	358.5 µs	323.5 µs	+10.8%
⚡	Simulation	chunked_varbinview_opt_canonical_into[(1000, 10)]	225.3 µs	188.6 µs	+19.51%
⚡	Simulation	chunked_varbinview_into_canonical[(1000, 10)]	211.3 µs	175.8 µs	+20.17%

Tip

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_{Comparing rk/buffermut_check_overflow (fa513af) with develop (d25c33f)}

[joseph-isaacs]

I still think our buffer should assert non zst at compile time