This issue will serve as the meta-issue for making partial statistics collection "at extremes" production ready and enabling it by default.

• sql/stats: addOuterBuckets logic breaks CREATE STATISTICS USING EXTREMES #93094
• sql/stats: merged partial statistics have inaccurate distinct counts #126730
• sql/stats: can't merge partial and full statistics with outer buckets #126822
• sql/stats: add variables to disable partial statistics merging and usage #95233
• sql/stats: don't use a nil eval context when merging statistics #126856
• sql/stats: after inject or restore of partial statistics, cannot create merged statistics #94101
• sql/stats: disable partial stats using extremes for enum and bool type columns #126401

PR to enable partial stats at extremes: #127850

Jira issue: CRDB-39681