Linux Audit Logs: OCSF pipeline style guide fixes (DataDog#24304)

* Apply OCSF style guide fixes to linux audit logs pipeline.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* Fix EXECVE actor mapper and facet conflicts flagged by CI.

Add ocsf.actor.app_name self-map to Process Activity EXECVE pipeline
so the backend validator sees at least one actor mapper. Fix three
facet definitions conflicting with other integrations: rename
ocsf.device.ip to "Device IP", add facetType/type to
ocsf.dst_endpoint.port and ocsf.time.

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Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: cepolation-datadog