x-pack/filebeat: Update CODEOWNERS for the new Salesforce's filebeat input

[shmsr]

Proposed commit message

See title.

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

• Relates x-pack/filebeat/input/salesforce: Implement a new Salesforce input #37331

[mergify]

This pull request does not have a backport label.
If this is a bug or security fix, could you label this PR @shmsr? 🙏.
For such, you'll need to label your PR with:

• The upcoming major version of the Elastic Stack
• The upcoming minor version of the Elastic Stack (if you're not pushing a breaking change)

To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-v8./d.0 is the label to automatically backport to the 8./d branch. /d is the digit

[shmsr]

Ping @elastic/ingest-eng-prod for approval.

[elasticmachine]

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• Start Time: 2024-03-28T09:25:36.443+0000

• Duration: 13 min 45 sec

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Total	3

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