[Release 3.0] Planned Breaking Changes for 3.0 in Plugin

[peterzhuamazon]

[Release 3.0] Planned Breaking Changes for 3.0 in Plugin

As mentioned in this META Issue, we want to track and increase transparency around the breaking changes planned for the 3.0 release across participating plugins.

Please kindly document all planned breaking changes related to your plugin for 3.0 here, by sharing detailed information about the changes, expected impact, and any guidance for users or other teams to adapt to the changes.

If needed, please also prepare PRs on documentation-website changes as part of the 3.0 release process.

Overall, this would help us deliver a smooth and seamless upgrade experience.

Thanks.

[AWSHurneyt]

1. As mentioned in https://github.com/opensearch-project/alerting/issues/1781, destinations-related assets should be deprecated from the back, and frontend plugins
2. The job scheduler functionality of the alerting plugin should be deprecated, and instead integrate with the job scheduler plugin
   1. Depending on the 3.0 release timeline, this may be out of scope
3. Per document monitors should no longer support index patterns
   1. Consider whether to deprecate support for multiple indexes

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Common utils issue for reference - https://github.com/opensearch-project/common-utils/issues/768#issuecomment-2631837544

[andrross]

Catch All Triage - 1, 2, 3, 4, 5

[AWSHurneyt]

Per @Murali-Arigala, we will not be making any breaking changes for 3.0.