[8.19](backport #41508) [Heartbeat] Adds maintenance windows !!

[mergify]

Proposed commit message

Added maintenance windows in heartbeat in RFC 5545 format using rrule-go library, this makes it compatible with kibana alerting maintenance windows which are using the same format https://www.elastic.co/guide/en/kibana/current/maintenance-windows.html

This will allow us to simple pass values from alerting maintenance windows where those are applicable to synthetics monitors as heartbeat configs

example being

heartbeat.monitors:

- type: http
  id: my-monitor
  urls: ["http://localhost:9200"]
  maintenance_windows:
    - freq: daily
      dtstart: "2024-11-04T01:00:00.000Z"
      interval: 1
      byweekday: [MO, TU, WE, TH, FR]
      duration: 3600000

Limitations

• Only Daily, weekly, Monthly and Yearly Frequencies are allowed.
• If DTStart is older than 2 years, it will throw error.

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

Related issues

Use cases

Screenshots

Logs

---

This is an automatic backport of pull request #41508 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of f6fb08d has failed:

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Your branch is up to date with 'origin/8.19'.

You are currently cherry-picking commit f6fb08ddf.
  (fix conflicts and run "git cherry-pick --continue")
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Changes to be committed:
	modified:   CHANGELOG.next.asciidoc
	modified:   NOTICE.txt
	modified:   heartbeat/docs/monitors/monitor-common-options.asciidoc
	new file:   heartbeat/monitors/maintwin/maintwin.go
	new file:   heartbeat/monitors/maintwin/maintwin_test.go
	modified:   heartbeat/monitors/stdfields/stdfields.go
	modified:   heartbeat/monitors/task.go
	modified:   heartbeat/scheduler/scheduler.go
	modified:   heartbeat/scheduler/scheduler_test.go

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   go.mod
	both modified:   go.sum

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[elasticmachine]

Pinging @elastic/obs-ds-hosted-services (Team:obs-ds-hosted-services)

[mergify]

This pull request has not been merged yet. Could you please review and merge it @shahzad31? 🙏

[mergify]

This pull request has not been merged yet. Could you please review and merge it @shahzad31? 🙏

[mergify]

This pull request is now in conflicts. Could you fix it? 🙏
To fixup this pull request, you can check out it locally. See documentation: https://help.github.com/articles/checking-out-pull-requests-locally/

git fetch upstream
git checkout -b mergify/bp/8.19/pr-41508 upstream/mergify/bp/8.19/pr-41508
git merge upstream/8.19
git push upstream mergify/bp/8.19/pr-41508