[8.18](backport #42569) metricbeat: Update beat module with apm-server tail sampling monitoring metrics fields

[mergify]

Proposed commit message

Update metricbeat beat module mapping to add back missing apm-server tail sampling montioring metrics fields.

The fields were missed in #40127

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.

Disruptive User Impact

Author's Checklist

• [ ]

How to test this PR locally

• Start apm-server with monitoring
• Start standalone metricbeat with beat module
• Confirm that fields are mapped correctly in metricbeat-* data stream

Related issues

• Part of monitoring: apm-server not shiping tbs monitoring metrics apm-server#14247

Use cases

Screenshots

Logs

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This is an automatic backport of pull request #42569 done by [Mergify](https://mergify.com).

[botelastic]

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