cyberarkpas: Fix handling of non-array CAProperty

[adriansr]

What does this PR do?

Fixes handling of the CAProperties.CAProperty field included in events from the Cyberark PAS.

It can be an object instead of an array of objects when a single property is defined.

Also removes redundant event.ingested field.

Checklist

• I have reviewed tips for building integrations and this pull request is aligned with them.
• I have verified that all data streams collect metrics or logs.
• I have added an entry to my package's changelog.yml file.
• I have verified that Kibana version constraints are current according to guidelines.

[elasticmachine]

Pinging @elastic/security-external-integrations (Team:Security-External Integrations)

[elasticmachine]

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• Start Time: 2022-03-31T20:47:42.972+0000

• Duration: 16 min 26 sec

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Test	Results
Failed	0
Passed	87
Skipped	0
Total	87

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