Expect the null value with snapshot CapturedTables metric when skipping snapshotting

When skipping snapshotting, the CaptureTables mertic should keep consistent with RowsScanned, shouldn't set values to it.

In addition, the current set values method didn't apply the "snapshot.include.collection.list" filter if configured.

So should remove the override method getCapturedTables() and resume the inheritance relationship in class MySqlSnapshotChangeEventSourceMetrics.