[r2dbc] Deprecate pre-1.0 support

## Description

R2DBC API spec was finalized in 2022 when `1.0.0` was released. However there are still support and published artifacts for `0.9.x` version. These artifacts are used by no one https://mvnrepository.com/artifact/com.clickhouse/clickhouse-r2dbc_0.9.1

Start by locating the R2DBC support and the build or release configuration for the published 0.9.x artifacts; the issue names no specific files or tests. Establish which pre-1.0 support and artifacts are in scope, then verify that the resulting project state matches the intended deprecation.

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