Change default logging config to use `buffering` async logger

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Problem:
default `buffered-write` could stall node and WAL failover configs needs to be opt-in.
Since CRDB now has async logger `buffering`, could you update default logging configuration to use it instead of `buffered-writes`. It'll lead to best practice is used by default and avoid hard to debug situations.
https://www.cockroachlabs.com/docs/v24.3/configure-logs#default-logging-configuration

It's been discussed w/ Eng on slack https://cockroachlabs.slack.com/archives/C063CP41TG9/p1748024429360979?thread_ts=1748023305.537249&cid=C063CP41TG9

Jira issue: CRDB-50937

Start with the default logging configuration described in the linked CockroachDB documentation and trace where the `buffered-write` default is defined. Confirm how the `buffering` async logger is configured and ensure the resulting defaults make `buffered-writes` opt-in, then verify the documented default matches the implementation.

Written by the indexing model from the issue text.