[release/6.0] Query: Don't add grouping key to projection when Distinct is applied #28143
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Resolves #28039
Description
If we need to push current query into a subquery when query has group by operation, we add grouping key to projection so we can refer to them outside but that is incorrect if distinct is applied on the projection since it would change meaning of distinct.
Customer impact
Customers running query which are affected by scenario will get incorrect results.
How found
Customer reported on 6.0.5
Regression
Yes as reported by customer, it worked on 5.0.13
Testing
Added tests for affected scenario.
Risk
Low. Also added quirk to revert back to older behavior.