MySQL connector's `ts_sec` is set incorrectly

Regarding the ts_sec field in the source field of change events from the MySQL connector, the millisecond value gets divided by 1000 twice, once in BinlogReader, and once in SourceInfo. So the value in the payload is 1000 times smaller than it is supposed to be.

The division in SourceInfo.setBinlogTimestampSeconds() should be removed.

(Originally reported by Dennis Persson in the Debezium Users chat room.)