New integration for Chrony

[naoyukiseki]

What does this PR do?

This PR adds a new integration for chrony.

Motivation

Chrony is a widely used time‑synchronization tool. Having a Datadog integration for it would be very useful.

Review checklist

• PR has a meaningful title or PR has the no-changelog label attached
• Feature or bugfix has tests
• Git history is clean
• If PR impacts documentation, docs team has been notified or an issue has been opened on the documentation repo
• If this PR includes a log pipeline, please add a description describing the remappers and processors.

Additional Notes

Anything else we should know when reviewing?

[naoyukiseki]

The validate-owner-validator check was failed. But I am a Datadog employee, I believe it can be ignored.
https://github.com/DataDog/integrations-extras/pull/2943/checks?check_run_id=68693094502
Owner is a required internal-only field. Use a valid internal team handle. External contributors should leave this unset.

If I unset the CODEOWNERS, the gh-worker-mergegate-4580a3 / devflow/mergegate was failed.
https://github.com/DataDog/integrations-extras/pull/2943/checks?check_run_id=68691500644

[maycmlee]

Created DOCS-13854 for review.

[github-actions]

This pull request has not been updated for more than 21 days. If there are no updates to this PR within 7 days, it will be closed. If you'd like to re-open this PR after it's been closed, you can start from the latest master branch or pull the latest changes into your branch and create a new pull request.

[github-actions]

This pull request was not updated after an additional 7 days of no activity. If you would like to continue work on this PR, please re-open this PR or create a fresh branch off of the latest master branch.

[naoyukiseki]

Reopened and update the base branch.
Thanks!

[urseberry]

Can you make this into a numbered link like the other links in this doc? Numbered links are required for the translation process to work.

[urseberry]

Suggested change

	## Service Checks
	### Service Checks

[urseberry]

Suggested change

	- **`chrony.stratum`**: NTP stratum level (unitless)
	- **`chrony.systime`**: System time offset from NTP time (seconds)
	- **`chrony.frequency`**: Frequency offset (unitless, ppm)
	- **`chrony.residualfreq`**: Residual frequency (unitless, ppm)
	- **`chrony.skew`**: Skew (unitless, ppm)
	- **`chrony.rootdelay`**: Root delay (seconds)
	- **`chrony.rootdispersion`**: Root dispersion (seconds)

The integration build process automatically inserts all of the metrics from your metadata.csv file into the docs under this heading. You don't need to include them.