The `like` in `RemoveBackfillJob` in job_table.go is incorrect

[zimulala]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

tidb/ddl/job_table.go

Lines 938 to 946 in 21aa40f

	// RemoveBackfillJob removes the backfill jobs from the tidb_background_subtask table.
	// If isOneEle is true, removes all jobs with backfillJob's ddl_job_id, ele_id and ele_key. Otherwise, removes the backfillJob.
	func RemoveBackfillJob(sess *session, isOneEle bool, backfillJob *BackfillJob) error {
	sql := "delete from mysql.tidb_background_subtask"
	if !isOneEle {
	sql += fmt.Sprintf(" where task_key like \"%d_%s_%d_%d\"", backfillJob.JobID, hex.EncodeToString(backfillJob.EleKey), backfillJob.EleID, backfillJob.ID)
	} else {
	sql += fmt.Sprintf(" where task_key like \"%d_%s_%d_%%\"", backfillJob.JobID, hex.EncodeToString(backfillJob.EleKey), backfillJob.EleID)
	}

like and = are not the same.
Related PR: #41093.

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

https://github.com/pingcap/tidb/pull/39616/files#diff-91c692cc214077acc788fcaf2f92fb40d0a6c4aef3e34e3b6ed532677dac9f13R705-R707

3. What did you see instead (Required)

https://github.com/pingcap/tidb/pull/41093/files#diff-91c692cc214077acc788fcaf2f92fb40d0a6c4aef3e34e3b6ed532677dac9f13R943

4. What is your TiDB version? (Required)

master