Investigate window-function alias loss in planner snapshot expectations

[xiangfu0]

Motivation

pinot-query-planner/src/test/resources/queries/WindowFunctionPlans.json repeats the note TODO: Look into why aliases are getting ignored in the final plan across multiple cases.

That suggests either a genuine alias-propagation bug in the planner or stale expected outputs in the snapshot file.

Scope

• Determine whether aliases should survive to the final explain plan for these window queries.
• Fix planner behavior or refresh the plan snapshots.
• Remove the repeated TODO notes once expectations are stable.

Notes

Observed on upstream/master on April 15, 2026.