REGIONAL BY ROW: Let the database do the data homing

In multi-region applications, data homing is crucial for delivering low latency experiences to a global user base. Traditionally, developers had to write complex code to manage data placement across regions. CockroachDB's REGIONAL BY ROW feature simplifies this process by allowing automatic data homing based on the crdb_region column. This enables applications to maintain the simplicity of single-region deployment while benefiting from multi-region performance. Experiments show that a default REGIONAL BY ROW table performs similarly to manually partitioned tables, and auto-rehoming can further improve application performance under certain conditions.