fill batch id for ClearBallot

[yezr]

ClearBallotCvrReader should fill in batch id in line 107

        CastVoteRecord castVoteRecord =
            new CastVoteRecord(
                source.getContestId(),
                cvrData[CvrColumnField.ScanComputerName.ordinal()],
                cvrData[CvrColumnField.BoxID.ordinal()],
                cvrData[CvrColumnField.BallotID.ordinal()],
                cvrData[CvrColumnField.PrecinctID.ordinal()],
                null,
                usesLastAllowedRanking(rankings, null),
                rankings);