backupccl: flip bulkio.backup.split_keys_on_timestamps to true

Release note (sql change): BACKUPs of ranges containing extremely
large numbers of revisions to a single row no longer fail with
errors related to exceeding size limit.

pkg/ccl/backupccl/backup_processor.go

@@ -103,7 +103,7 @@ var (
 		settings.TenantWritable,
 		"bulkio.backup.split_keys_on_timestamps",
 		"split backup data on timestamps when writing revision history",
-		false,
+		true,
 	)
 )
 

pkg/ccl/backupccl/backup_test.go

@@ -6946,8 +6946,7 @@ INSERT INTO baz.bar VALUES (110, 'a'), (210, 'b'), (310, 'c'), (410, 'd'), (510,
 	systemDB.Exec(t, `SET CLUSTER SETTING kv.bulk_sst.target_size='10b'`)
 	systemDB.Exec(t, `SET CLUSTER SETTING kv.bulk_sst.max_allowed_overage='10b'`)
 
-	// Allow mid key breaks for the tennant to verify timestamps on resume.
-	tenant10.Exec(t, `SET CLUSTER SETTING bulkio.backup.split_keys_on_timestamps = true`)
+	// Test mid key breaks for the tenant to verify timestamps on resume.
 	tenant10.Exec(t, `UPDATE baz.bar SET v = 'z' WHERE i = 210`)
 	tenant10.Exec(t, `BACKUP DATABASE baz TO 'userfile://defaultdb.myfililes/test4' with revision_history`)
 	expected = nil