Incorrect results: leaf expression pushdown duplicates volatile expressions (random() evaluated twice)

[fornwall]

Describe the bug

enable_leaf_expression_pushdown inlines a column's defining expression into each extracted get_field that references it, but performs no volatility check.

To Reproduce

Run this:

datafusion-cli -c "SELECT s, s['a'] AS field FROM (SELECT named_struct('a', random()) AS s FROM generate_series(1,3));"

Expected behavior

field equals s.a on every row.

Additional context

Setting enable_leaf_expression_pushdown = false avoids the bug (makes field equals s.a on every row).

[fornwall]

Seems to be fixed by #23691 (but I have not reviewed or tested that PR extensively, just found that when searching around for the issue).

[fornwall]

Does not seem to be a regression, 53 and 54 have the same issue.