sql: Reorder show ranges output to be clearer

The output of show ranges had column orderings that at a quick glance
could lead to users making the wrong conclusions about their
partitioning setup. This PR adjusts the columns and adds more readily
accessible information about the lease_holder node's locality.

Fixes #40467.

Release note (sql change): Reorder columns in show ranges output

pkg/sql/delegate/show_ranges.go

@@ -42,9 +42,10 @@ func (d *delegator) delegateShowRanges(n *tree.ShowRanges) (tree.Statement, erro
 			END AS end_key,
 			range_id,
 			range_size / 1000000 as range_size_mb,
-			replicas,
 			lease_holder,
-			replica_localities,
+      replica_localities[1] as lease_holder_locality,
+			replicas,
+			replica_localities
 		FROM %[1]s.crdb_internal.ranges AS r
 		WHERE database_name=%[2]s
 		ORDER BY table_name, r.start_key
@@ -71,8 +72,9 @@ SELECT
   CASE WHEN r.end_key >= x'%s' THEN NULL ELSE crdb_internal.pretty_key(r.end_key, 2) END AS end_key,
   range_id,
   range_size / 1000000 as range_size_mb,
-  replicas,
   lease_holder,
+  replica_localities[1] as lease_holder_locality,
+  replicas,
   replica_localities
 FROM crdb_internal.ranges AS r
 WHERE (r.start_key < x'%s')

pkg/sql/show_ranges_test.go

@@ -36,11 +36,12 @@ func TestShowRangesWithLocality(t *testing.T) {
 	sqlDB.Exec(t, `CREATE TABLE t (x INT PRIMARY KEY)`)
 	sqlDB.Exec(t, `ALTER TABLE t SPLIT AT SELECT i FROM generate_series(0, 20) AS g(i)`)
 
-	const replicasColIdx = 4
-	const localitiesColIdx = 6
+	const replicasColIdx = 0
+	const localitiesColIdx = 1
 	replicas := make([]int, 3)
 
-	result := sqlDB.QueryStr(t, `SHOW RANGES FROM TABLE t`)
+	q := `SELECT replicas, replica_localities from [SHOW RANGES FROM TABLE t]`
+	result := sqlDB.QueryStr(t, q)
 	for _, row := range result {
 		_, err := fmt.Sscanf(row[replicasColIdx], "{%d,%d,%d}", &replicas[0], &replicas[1], &replicas[2])
 		if err != nil {