push_down_leaf_projections fails for self joins in some scenarios

[cetra3]

Describe the bug

Some special shapes of queries, namely self joins on structs/json data trip up the push down leaf expressions optimiser.

To Reproduce

From datafusion-cli:

  CREATE TABLE t AS SELECT named_struct('a', 'x', 'b', 'y') AS s, 1 AS id;

  SELECT p.s['a'], count(1)
  FROM t p
  LEFT JOIN t c ON p.id = c.id
  WHERE c.s['b'] IS NOT NULL
  GROUP BY 1;

Will produce:

Optimizer rule 'push_down_leaf_projections' failed
caused by
Schema error: Schema contains qualified field name p.__datafusion_extracted_1
and unqualified field name __datafusion_extracted_1 which would be ambiguous

Expected behavior

Should output something like:

+--------+-----------------+
| p.s[a] | count(Int64(1)) |
+--------+-----------------+
| x      | 1               |
+--------+-----------------+

Additional context

No response