Add x-pack-auditbeat to conf.yaml

[karenzone]

~DO NOT MERGE until after https://github.com/elastic/beats/pull/40357 and https://github.com/elastic/beats/pull/40370 have been merged.~ - DONE

This PR is required to validate and pass docs-ci for https://github.com/elastic/beats/pull/40252.

Related issue: https://github.com/elastic/beats/issues/40186 Related PR: https://github.com/elastic/beats/pull/40252

Update conf.yaml to add x-pack-auditbeat in order to support add-session-metadata for Session View

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[karenzone]

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[karenzone]

11962

[bmorelli25]

3.14