backup job will log the mysql password dsn when connection failed

[tennix]

Bug Report

When backup job cannot connect to tidb, for example if the host is misconfigured, the log will show:

Create rclone.conf file.
/tidb-backup-manager backup --namespace=tennix --backupName=tidb-backup-09j680i1-2020-05-20t10-08-00
I0520 10:09:45.009649       1 backup.go:71] start to process backup tennix/tidb-backup-09j680i1-2020-05-20t10-08-00
W0520 10:09:45.014951       1 manager.go:104] can't connect to tidb cluster tennix/tidb-backup-09j680i1-2020-05-20t10-08-00, err: cannot connect to mysql: root:my-secret-password$5@(db-tidb:4000)/mysql?charset=utf8, err: dial tcp: lookup db-tidb on 172.20.0.10:53: no such host
W0520 10:09:50.020298       1 manager.go:104] can't connect to tidb cluster tennix/tidb-backup-09j680i1-2020-05-20t10-08-00, err: cannot connect to mysql: root:my-secret-password$5@(db-tidb:4000)/mysql?charset=utf8, err: dial tcp: lookup db-tidb on 172.20.0.10:53: no such host
W0520 10:09:55.020103       1 manager.go:104] can't connect to tidb cluster tennix/tidb-backup-09j680i1-2020-05-20t10-08-00, err: cannot connect to mysql: root:my-secret-password$5@(db-tidb:4000)/mysql?charset=utf8, err: dial tcp: lookup db-tidb on 172.20.0.10:53: no such host
W0520 10:10:00.023846       1 manager.go:104] can't connect to tidb cluster tennix/tidb-backup-09j680i1-2020-05-20t10-08-00, err: cannot connect to mysql: root:my-secret-password$5@(db-tidb:4000)/mysql?charset=utf8, err: dial tcp: lookup db-tidb on 172.20.0.10:53: no such host
W0520 10:10:05.172621       1 manager.go:104] can't connect to tidb cluster tennix/tidb-backup-09j680i1-2020-05-20t10-08-00, err: cannot connect to mysql: root:my-secret-password$5@(db-tidb:4000)/mysql?charset=utf8, err: dial tcp: lookup db-tidb on 172.20.0.10:53: no such host
W0520 10:10:10.177223       1 manager.go:104] can't connect to tidb cluster tennix/tidb-backup-09j680i1-2020-05-20t10-08-00, err: cannot connect to mysql: root:my-secret-password$5@(db-tidb:4000)/mysql?charset=utf8, err: dial tcp: lookup db-tidb on 172.20.0.10:53: no such host
W0520 10:10:15.464478       1 manager.go:104] can't connect to tidb cluster tennix/tidb-backup-09j680i1-2020-05-20t10-08-00, err: cannot connect to mysql: root:my-secret-password$5@(db-tidb:4000)/mysql?charset=utf8, err: dial tcp: lookup db-tidb on 172.20.0.10:53: no such host
W0520 10:10:21.994972       1 manager.go:104] can't connect to tidb cluster tennix/tidb-backup-09j680i1-2020-05-20t10-08-00, err: cannot connect to mysql: root:my-secret-password$5@(db-tidb:4000)/mysql?charset=utf8, err: dial tcp: lookup db-tidb on 172.20.0.10:53: no such host
W0520 10:10:25.020383       1 manager.go:104] can't connect to tidb cluster tennix/tidb-backup-09j680i1-2020-05-20t10-08-00, err: cannot connect to mysql: root:my-secret-password$5@(db-tidb:4000)/mysql?charset=utf8, err: dial tcp: lookup db-tidb on 172.20.0.10:53: no such host
W0520 10:10:31.025749       1 manager.go:104] can't connect to tidb cluster tennix/tidb-backup-09j680i1-2020-05-20t10-08-00, err: cannot connect to mysql: root:my-secret-password$5@(db-tidb:4000)/mysql?charset=utf8, err: dial tcp 172.20.181.90:4000: connect: connection refused
W0520 10:10:36.017825       1 manager.go:104] can't connect to tidb cluster tennix/tidb-backup-09j680i1-2020-05-20t10-08-00, err: cannot connect to mysql: root:my-secret-password$5@(db-tidb:4000)/mysql?charset=utf8, err: dial tcp 172.20.181.90:4000: connect: connection refused
W0520 10:10:41.041762       1 manager.go:104] can't connect to tidb cluster tennix/tidb-backup-09j680i1-2020-05-20t10-08-00, err: cannot connect to mysql: root:my-secret-password$5@(db-tidb:4000)/mysql?charset=utf8, err: dial tcp 172.20.181.90:4000: connect: connection refused
I0520 10:10:45.032862       1 backup_status_updater.go:66] Backup: [tennix/tidb-backup-09j680i1-2020-05-20t10-08-00] updated successfully
I0520 10:10:45.037120       1 manager.go:152] cluster tennix/tidb-backup-09j680i1-2020-05-20t10-08-00 tikv_gc_life_time is 72h

We must not log this error message.