Fix SortExec discards field metadata on the output schema

[alamb]

Which issue does this PR close?

Closes #1476

Rationale for this change

This is a regression introduced in #1455

The following code in Sort skips the field level metadata when when it constructs the output batch.

    let schema = Arc::new(Schema::new(
        schema
            .fields()
            .iter()
            .zip(batch.columns().iter().map(|col| col.data_type()))
            .map(|(field, ty)| Field::new(field.name(), ty.clone(), field.is_nullable()))
            .collect::<Vec<_>>(),
    ));

Thus the output schema is not correct.

It also seems to be unnecessary (at least all the tests pass without it, so maybe @maxburke can comment on what problem it was solving).

@hntd187 has also added some functions working with apache/arrow-rs#1033 PR to add some additional functions for creating fields and I will work on this as well

What changes are included in this PR?

1. Remove offending code
2. add a test

Are there any user-facing changes?

Bug fix

[alamb]

the fix is to delete this code, the rest of the PR is a test

[Dandandan]

Nice and clean 🧹🧼

[hntd187]

This is just to correct the bug correct? We will deal with carrying over metadata properly in another PR?

[alamb]

This is just to correct the bug correct? We will deal with carrying over metadata properly in another PR?

Yes -- I think DataFusion does carry over metadata now in many cases and this PR corrects a case where the metadata used to be carried over but is no longer

[maxburke]

@alamb If I recall the reason this change was made was because in our cases the schema was stripped of the timezone information but the underlying record batches preserved it.

[alamb]

@alamb If I recall the reason this change was made was because in our cases the schema was stripped of the timezone information but the underlying record batches preserved it.

I am sorry if I broke something for you @maxburke -- if you help me understand / write a reproducer for what want to do I am happy to help try and make it work