[8.19](backport #46313) improve: use SetupMetricsOptions instead of SetupMetrics

[mergify]

Proposed commit message

The problem is that SetupMetrics in elastic-agent-system-metrics is conditionally compiled and only available when the build tags (darwin && cgo) || (freebsd && cgo) || linux || windows are satisfied. If you build on Darwin without cgo, it won't be compiled, hence the undefined symbol.

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.

---

This is an automatic backport of pull request #46313 done by [Mergify](https://mergify.com).

[mergify]

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	both modified:   libbeat/cmd/instance/beat.go

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[elasticmachine]

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