[RAC] Build a consolidated implementation in Rule Registry (Draft)

[banderror]

Ticket: #101016

Summary

This is a draft of the consolidated implementation of index management for RAC indices (see #98912).

TODO:

• Build a draft consolidated implementation based on [RAC] Rule monitoring: Event Log for Rule Registry #98353 (evolve it into a consolidated implementation).
• Explain what decisions has been made regarding the new implementation (interface, implementation details), and how it's supposed to work. Compare the 3 implementations (the 2 previous and the consolidated one). Update [RAC][Meta] Consolidate the two indexing implementations in rule_registry plugin #101016 with that info in the comments.
• Migrate clients already using rule_registry to the consolidated implementation.
• Remove all leftovers from the 2 previous implementations.
• Integrate RBAC ([RAC] [RBAC] MVP RBAC for alerts as data #100705) into the final implementation?

Checklist

Delete any items that are not applicable to this PR.

• Any text added follows EUI's writing guidelines, uses sentence case text and includes i18n support
• Documentation was added for features that require explanation or tutorials
• Unit or functional tests were updated or added to match the most common scenarios
• Any UI touched in this PR is usable by keyboard only (learn more about keyboard accessibility)
• Any UI touched in this PR does not create any new axe failures (run axe in browser: FF, Chrome)
• If a plugin configuration key changed, check if it needs to be allowlisted in the cloud and added to the docker list
• This renders correctly on smaller devices using a responsive layout. (You can test this in your browser)
• This was checked for cross-browser compatibility

Risk Matrix

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Before closing this PR, invite QA, stakeholders, and other developers to identify risks that should be tested prior to the change/feature release.

When forming the risk matrix, consider some of the following examples and how they may potentially impact the change:

Risk	Probability	Severity	Mitigation/Notes
Multiple Spaces—unexpected behavior in non-default Kibana Space.	Low	High	Integration tests will verify that all features are still supported in non-default Kibana Space and when user switches between spaces.
Multiple nodes—Elasticsearch polling might have race conditions when multiple Kibana nodes are polling for the same tasks.	High	Low	Tasks are idempotent, so executing them multiple times will not result in logical error, but will degrade performance. To test for this case we add plenty of unit tests around this logic and document manual testing procedure.
Code should gracefully handle cases when feature X or plugin Y are disabled.	Medium	High	Unit tests will verify that any feature flag or plugin combination still results in our service operational.
See more potential risk examples

For maintainers

• This was checked for breaking API changes and was labeled appropriately

[xcrzx]

We'll probably need to return the error here or rethrow it. So we can properly handle errors in the caller methods.

[xcrzx]

What about renaming the methods of this class to make things a little bit more clear?
indexManyNow -> indexMany
indexOne -> enqueueOne
indexMany -> qnqueueMany

[kibanamachine]

💔 Build Failed

• continuous-integration/kibana-ci/pull-request
• Commit: fa04b8d
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Failed CI Steps

• Lint: eslint

Metrics [docs]

✅ unchanged

History

• 💔 Build #131207 failed 897b4a76f559c19e28c4df85b2def3f6092af527
• 💔 Build #131039 failed ada916f
• 💚 Build #130865 succeeded e087a1a918ae92636633c833919cfe30a3ee5da0
• 💔 Build #130861 failed 6733d091e56e676851a48655a4dc25619ca91d39

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream

cc @banderror