[AO] Fix alerting rules order (#168013)

Closes #167876

## Summary

This PR fixes alerting rules order. Since the Custom threshold rule is
in the tech preview, we want to show it at the end of the list.

|Rules (trial)|Rules (Permium)|
|---|---|

|![image](https://github.com/elastic/kibana/assets/12370520/6e542d8d-a2d8-4dc9-8728-c55bacc87592)|![image](https://github.com/elastic/kibana/assets/12370520/da5c2a82-a5f1-4cb3-aa3c-183fa7af3fa3)|

x-pack/plugins/observability/public/hooks/use_get_filtered_rule_types.ts

@@ -13,6 +13,6 @@ export function useGetFilteredRuleTypes() {
   const { observabilityRuleTypeRegistry } = usePluginContext();
 
   return useMemo(() => {
-    return [...observabilityRuleTypeRegistry.list(), ES_QUERY_ID];
+    return [ES_QUERY_ID, ...observabilityRuleTypeRegistry.list()];
   }, [observabilityRuleTypeRegistry]);
 }

x-pack/plugins/observability/public/rules/register_observability_rule_types.ts

@@ -125,7 +125,7 @@ export const registerObservabilityRuleTypes = (
       alertDetailsAppSection: lazy(
         () => import('../components/custom_threshold/components/alert_details_app_section')
       ),
-      priority: 110,
+      priority: 5,
     });
   }
 };