[8.9] [DOCv2] Temporarily disable Kibana Rules (#126869) (#161865)

# Backport

This will backport the following commits from `main` to `8.9`:
- [[DOCv2] Temporarily disable Kibana Rules
(#126869)](#126869)

<!--- Backport version: 8.9.7 -->

### Questions ?
Please refer to the [Backport tool
documentation](https://github.com/sqren/backport)

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Temporarily disable Kibana Rules (#126869)\n\n👋🏼 @gchaps asked me to
file a new PR since my
last\r\nhttps://github.com//pull/122573 got too far
behind.\r\n\r\n## Summary\r\n\r\n🙏🏼 per #116017, adds insight on how to
temporarily disable Kibana Rules\r\nfor clusters which need breathing
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Temporarily disable Kibana Rules (#126869)\n\n👋🏼 @gchaps asked me to
file a new PR since my
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Temporarily disable Kibana Rules (#126869)\n\n👋🏼 @gchaps asked me to
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BACKPORT-->

Co-authored-by: Stef Nestor <26751266+stefnestor@users.noreply.github.com>

docs/user/alerting/alerting-troubleshooting.asciidoc

@@ -189,12 +189,30 @@ In addition to the above methods, refer to the following approaches and common i
 * <<event-log-index,Querying event log index>>
 * <<testing-connectors,Testing connectors using {connectors-ui} UI and the `kbn-action` tool>>
 
+[discrete]
+[[alerting-kibana-throttle]]
+==== Temporarily throttle all tasks
+
+If cluster performance becomes degraded from excessive or expensive rules and {kib} is sluggish or unresponsive, you can temporarily reduce load to the Task Manager by updating its <<task-manager-settings-kb,settings>>:
+
+[source,txt]
+--------------------------------------------------
+xpack.task_manager.max_workers: 1
+xpack.task_manager.poll_interval: 1h
+--------------------------------------------------
+
+[WARNING]
+====
+This approach should be used only temporarily as a last resort to restore function to {kib} when it is unresponsive and attempts to identify and <<controlling-rules,snooze or disable>> slow-running rules have not fixed the situation.
+It severely throttles all background tasks, not just those relating to {alert-features}. The task manager will run only one task at a time and will look for more work each hour.
+====
+
 [discrete]
 [[alerting-limitations]]
 === Limitations
 
 The following limitations and known problems apply to the {version} release of
-the {kib} {alert-features}. 
+the {kib} {alert-features}:
 
 [discrete]
 ==== Alert visibility
@@ -208,3 +226,4 @@ the `consumer` property.
 include::troubleshooting/alerting-common-issues.asciidoc[]
 include::troubleshooting/event-log-index.asciidoc[]
 include::troubleshooting/testing-connectors.asciidoc[]
+