release-22.1: sql: execute batch statements in an implicit transaction

[cockroach-teamcity]

Exalate commented:

cockroachdb/cockroach#77865 --- Release note (sql change): The enable_implicit_transaction_for_batch_statements session variable was added. It defaults to true. When it is true, multiple statements in a single query (a.k.a. a "batch statement") will all be run in the same implicit transaction, which matches the Postgres wire protocol. This setting is provided for users who want to preserve the behavior of CockroachDB versions v21.2 and earlier.

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update: see #13269 -- we decided that we'd actually make enable_implicit_transaction_for_batch_statements false by default for v22.1. For v22.2 in the fall, it will be true by default.

Jira Issue: DOC-2913

Jira Issue: DOC-4376