Use appropriate return type for byte vector specific cosineBody* functions

[kaivalnp]

Description

Intermediate cast from int -> float -> int in the byte vector specific cosineBody function(s) loses precision.

This happens for integers >= 2^24, because IEEE 754 single-precision floats use 24 bits to represent the integer part.

For example, when 16777217 is cast to float and back to int, it yields 16777216.

This also avoids CPU cycles related to casting. VectorUtilBenchmark shows minor but consistent speedup:

main

Benchmark                               (size)   Mode  Cnt  Score   Error   Units
VectorUtilBenchmark.binaryCosineVector    1024  thrpt   15  4.782 ± 0.007  ops/us

This PR

Benchmark                               (size)   Mode  Cnt  Score   Error   Units
VectorUtilBenchmark.binaryCosineVector    1024  thrpt   15  4.885 ± 0.002  ops/us

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[benwtrent]

simplifies things, fine with this :)

[msokolov]

Let's merge then? and maybe backport?

[kaivalnp]

Thanks @msokolov, I opened #15298 to backport