[YCQL] Add support for dumping of BATCH statements on http endpoint.

[divchaturvedi]

Jira Link: DB-7096

Description

Currently prepared statements stats are being dumped on the endpoint localhost:12000/statements. Support to dump the batch statements statistics needs to be added.

487d628 introduces support to dump prepared statements stats. Since batch statements consist of prepared and unprepared statements, we can use the existing pipeline to dump batch statements stats.

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