Fix column name for COUNT(*) set by AggregateStatistics

[qrilka]

This fixes the issue of column name COUNT(UInt8) appearing instead of COUNT(*)

Which issue does this PR close?

Closes #104.

Rationale for this change

This should make produced column name consistent with the input SQL

What changes are included in this PR?

Are these changes tested?

Tested with cargo test

Are there any user-facing changes?

Changes column name for this particular case

[qrilka]

The failure in in cargo test doc seems to happen in CI itself

[alamb]

The failure in in cargo test doc seems to happen in CI itself

I believe it was fixed by #7753

Indeed -- https://github.com/apache/arrow-datafusion/actions/runs/6434063712/job/17472738458?pr=7757 looks like some infrastructure error

warning: spurious network error (1 tries remaining): [7] Couldn't connect to server (Failed to connect to crates.io port 443 after 0 ms: Couldn't connect to server)
warning: spurious network error (1 tries remaining): [7] Couldn't connect to server (Failed to connect to crates.io port 443 after 0 ms: Couldn't connect to server)
error: failed to download from `[https://crates.io/api/v1/crates/arrow-schema/47.0.0/download`](https://crates.io/api/v1/crates/arrow-schema/47.0.0/download%60)

Caused by:
  [7] Couldn't connect to server (Failed to connect to crates.io port 443 after 0 ms: Couldn't connect to server)
Error: Process completed with exit code 101.

[alamb]

Thank you @qrilka 🙏 this looks great

I also tried it locally:

DataFusion CLI v31.0.0
❯ select count(*) from (select 1);
+----------+
| COUNT(*) |
+----------+
| 1        |
+----------+
1 row in set. Query took 0.007 seconds.

[alamb]

I think this covers the output as well.

[alamb]

I restarted the doc test

[alamb]

Closes #104.

This might be the lowest ticket we have had closed in a while 🏆