Join dynamic filter pushdown through `ProjectionExec` can map duplicate output aliases to the wrong expression

[haohuaijin]

Describe the bug

Enabling join dynamic filter pushdown can silently discard a matching row when the filter passes through a ProjectionExec whose output has two columns with the same alias (here a.id and b.id, both named id).

With the same data and SQL, disabling datafusion.optimizer.enable_join_dynamic_filter_pushdown returns one row; enabling it returns zero rows, without an error.

To Reproduce

Run the following SQL in a fresh datafusion-cli session. The two /tmp/ Parquet paths must not already exist.

SET datafusion.optimizer.join_reordering = false;

COPY (SELECT 'a1' AS id, 'x1' AS ty)
TO '/tmp/df_dynamic_filter_projection_a.parquet'
STORED AS PARQUET;

COPY (SELECT 'x1' AS id)
TO '/tmp/df_dynamic_filter_projection_b.parquet'
STORED AS PARQUET;

CREATE EXTERNAL TABLE ta
STORED AS PARQUET
LOCATION '/tmp/df_dynamic_filter_projection_a.parquet';

CREATE EXTERNAL TABLE tb
STORED AS PARQUET
LOCATION '/tmp/df_dynamic_filter_projection_b.parquet';

-- Returns one row: (a1, a1, x1, x1!).
SET datafusion.optimizer.enable_join_dynamic_filter_pushdown = false;

SELECT s.id, a.id, b.id, tag
FROM ta s
JOIN (
    SELECT a.id, b.id, a.ty || '!' AS tag
    FROM ta a JOIN tb b ON a.ty = b.id
)
ON s.id = a.id;

-- Incorrectly returns zero rows.
SET datafusion.optimizer.enable_join_dynamic_filter_pushdown = true;

SELECT s.id, a.id, b.id, tag
FROM ta s
JOIN (
    SELECT a.id, b.id, a.ty || '!' AS tag
    FROM ta a JOIN tb b ON a.ty = b.id
)
ON s.id = a.id;

Expected behavior

No response

Additional context

ProjectionExec resolves pushed-down filter columns by output alias instead of by position, so with two outputs named id the filter on b.id is rewritten to a.id. Found while working on #25244; the fix is included in #25259.