TTL Job summary is empty when the job timeout

[YangKeao]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

1. Run a TTL job until timeout (6h).

2. What did you expect to see? (Required)

The tidb_ttl_table_status and tidb_ttl_job_history will include the job summary like deleted row counts:

3. What did you see instead (Required)

The rows counts are always 0.

{"total_rows":0,"success_rows":0,"error_rows":0,"total_scan_task":0,"scheduled_scan_task":0,"finished_scan_task":0,"scan_task_err":"job is timeout"}

4. What is your TiDB version? (Required)