[Backport 2.12] v2.12 update roles.yml with new API for experimental alerting plugin feature #4027

[AWSHurneyt]

Description

We added a new API to the alerting plugin to support enhancements to the UI (link). The enhancements allow users to configure per query, and per bucket monitors that can query remote clusters via the UI. Previously, such monitors could only be configured using devtools/API commands.

In addition, we added support for configuring cluster metrics monitors which can execute various API (link to full list of supported API) against remote clusters. The new API is used by the frontend to also support creating these monitors via the UI.

• Category (Enhancement, New feature, Bug fix, Test fix, Refactoring, Maintenance, Documentation)
  • New experimental feature
  • Enhancement to existing features
• Why these changes are required?
  • To include this API permission in the reserved role that's shipped with the default distribution of OpenSearch.
• What is the old behavior before changes and new behavior after changes?
  • This API was not available before the experimental launch. With the experimental feature enabled, this API can be used to retrieve a list of connect remote clusters, the indexes/aliases on those clusters along with their health statuses, and optionally the mappings for those indexes.

Issues Resolved

opensearch-project/alerting-dashboards-plugin#796

Is this a backport? If so, please add backport PR # and/or commits #
#4027

Testing

Executed E2E tests with and without the experimental feature enabled to help ensure no regressions.

Check List

• New functionality includes testing
• New functionality has been documented
• Commits are signed per the DCO using --signoff

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