pgsql: Fix HashAgg regression from choosing too many initial buckets.

Fix HashAgg regression from choosing too many initial buckets. Diagnosis by Andres. Reported-by: Pavel Stehule Discussion: https://postgr.es/m/CAFj8pRDLVakD5Aagt3yZeEQeTeEWaS3YE5h8XC3Q3qJ6TYkc2Q%40mail.gmail.com Backpatch-through: 13 Branch -- REL_13_STABLE Details --- https://git.post

pgsql: Fix HashAgg regression from choosing too many initial buckets.

Fix HashAgg regression from choosing too many initial buckets. Diagnosis by Andres. Reported-by: Pavel Stehule Discussion: https://postgr.es/m/CAFj8pRDLVakD5Aagt3yZeEQeTeEWaS3YE5h8XC3Q3qJ6TYkc2Q%40mail.gmail.com Backpatch-through: 13 Branch -- master Details --- https://git.postgresql.