Mark cyberark module as deprecated

[adriansr]

What does this PR do?

Marks Filebeat's cyberark module as deprecated.

Why is it important?

The new cyberarkpas module replaces the RSA2Elk-generated cyberark.

Checklist

• [ ] My code follows the style guidelines of this project
• [ ] I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files
• [ ] I have added tests that prove my fix is effective or that my feature works
• I have added an entry in CHANGELOG.next.asciidoc or CHANGELOG-developer.next.asciidoc.

Related issues

• Closes: [Cyberark] Deprecate experimental Cyberark Filebeat Module + Integration #25261

Screenshots

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

[elasticmachine]

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Build stats

• Build Cause: adriansr commented: /test

• Start Time: 2021-05-04T07:35:56.962+0000

• Duration: 116 min 5 sec

• Commit: 11e6fda

Test stats 🧪

Test	Results
Failed	0
Passed	8125
Skipped	1639
Total	9764

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Test stats 🧪

Test	Results
Failed	0
Passed	8125
Skipped	1639
Total	9764

[adriansr]

/test