Update kafka appender dependency and uses

[VedarthConfluent]

Description

Fix kafka log4j appender dependency usecases and docs.
Kafka log4j appender is deprecated and now log4j's own KafkaAppender will be used.

Testing done

Describe the testing strategy. Unit and integration tests are expected for any behavior changes.

Reviewer checklist

• Ensure docs are updated if necessary. (eg. if a user visible feature is being added or changed).
• Ensure relevant issues are linked (description should include text like "Fixes #")
• Do these changes have compatibility implications for rollback? If so, ensure that the ksql command version is bumped.

[confluent-cla-assistant]

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