Parquet writer should not write any min/max data to ColumnIndex when all values are null

[etseidl]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.
While investigating #6310 I noticed that when a page contains only null values, min and max for that page will be set to vec![0; 1]. Because of this, a byte array of length 1 will be written. Instead an empty vec should be passed so spurious min/max values are not produced.

Describe the solution you'd like
Rather than vec![0; 1], vec![] should be passed to ColumnIndexBuilder::append. This will reduce the column index size a tiny bit.

Describe alternatives you've considered
It could be the current behavior is desired, so no change would be necessary.

Additional context
The current behavior isn't a bug, but is a little wasteful.

[etseidl]

take

[alamb]

label_issue.py automatically added labels {'parquet'} from #6316