Publically re-export rand with test_utils

[alamb]

Which issue does this PR close?

• Related to Release arrow-rs / parquet major version 55.0.0 (Apr 2025) #7084

Rationale for this change

As we found out here rand appears in some public APIs and thus it should be available to use with just arrow

For example, in DataFusion we have

https://github.com/apache/datafusion/blob/dfc4ba31ed26fbc84eebb0c39b96ebd8f2c11267/datafusion/functions-aggregate/benches/array_agg.rs#L51-L58

(namely randomly generating a LIstArray using the create_primitive_array function from bench_utils)

Being able to have datafusion's benchmark use the same rand / distribution would let us use both versions

It may just be better to avoid using the arrow bench_utils at all.

What changes are included in this PR?

Propose publically re-exporting rand and using that re-export in the public APIs

Are there any user-facing changes?

New public export when test_utils feature is enabled

[alamb]

I don't feel strongly about this and if it is not wanted we can just close this PR

[tustvold]

I am largely indifferent to this

[mbrobbel]

It may just be better to avoid using the arrow bench_utils at all.

+1

But it's also a good idea to merge this.

[alamb]

It may just be better to avoid using the arrow bench_utils at all.

+1

But it's also a good idea to merge this.

What do we think about merging this and marking all of bench_utils as deprecated (pointing out that external users should just copy the code into their repo if they want to use them) 🤔