fix(metricbeat): Accept Float values as float not long

[ash-darin]

Proposed commit message

Fix Docker values to take into account floating point numbers

Metricbeat outputs floats, as evident here: Link to source that produces these values, as these are not absolute values but values for a fraction of a time ("per_second").

But with the exception of the "dropped" values, these are treated as long and therefore simply truncated. To preserve the values to a certain degree, treat all incoming ("in") and outgoing ("out") values as floats, like "dropped".

In GO, float64 is a IEEE754 conforming 64bit floating point number.
in Elastricsearch double is a IEEE754 conforming 64bit floating point number.

Therefore mapping these values to double is the closest match to any possible values produced by metricbeat.

Checklist

• My code follows the style guidelines of this project

Disruptive User Impact

This should not disrupt user experience.

Use cases

You can now evaluate the values with a higher degree of accuracy.

[github-actions]

🤖 GitHub comments

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• run docs-build : Re-trigger the docs validation. (use unformatted text in the comment!)

[mergify]

This pull request does not have a backport label.
If this is a bug or security fix, could you label this PR @ash-darin? 🙏.
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-8./d is the label to automatically backport to the 8./d branch. /d is the digit
• backport-active-all is the label that automatically backports to all active branches.
• backport-active-8 is the label that automatically backports to all active minor branches for the 8 major.
• backport-active-9 is the label that automatically backports to all active minor branches for the 9 major.

[elasticmachine]

Pinging @elastic/elastic-agent-data-plane (Team:Elastic-Agent-Data-Plane)