Add checks to "RENAME X to event.original" processors across Filebeat module pipelines

[rseldner]

Describe the enhancement: Update filebeat module pipelines to include a conditional check for the existence of event.original

Describe a specific use case for the enhancement or feature:

When renaming a field to event.original, it appears the ingest pipelines for filebeat modules generally do not take into account whether event.original already exists, which can occur when using Logstash. This can result in "field [event.original] already exists" errors.

This has been addressed in elastic agent integrations' pipelines by including a conditional check:
if: ctx.event?.original == null PR: https://github.com/elastic/integrations/issues/7822

It would be nice to implement the same logic in the filebeat ingest pipelines.

Example:

Filebeat IIS Module	IIS Integration
- rename: field: message target_field: event.original	- rename: field: message target_field: event.original ignore_missing: true if: 'ctx.event?.original == null'