[Response Ops][Alerting] Only load maintenance windows when there are…

… alerts during rule execution and caching loaded maintenance windows (#192573)

Resolves #184324

## Summary

This PR moves the loading of maintenance windows further down in rule
execution so maintenance windows are only loaded when a rule execution
generates alerts. Also caches maintenance windows per space to reduce
the number of requests.

## To Verify

1. Add some logging to
x-pack/plugins/alerting/server/task_runner/maintenance_windows/maintenance_windows_service.ts
to indicate when windows are being fetched and when they're returning
from the cache.
2. Create and run some rules in different spaces with and without alerts
to see that the maintenance windows are only loaded when there are
alerts and that the windows are returned from the cache when the cache
has not expired.

---------

Co-authored-by: Elastic Machine <elasticmachine@users.noreply.github.com>
Co-authored-by: kibanamachine <42973632+kibanamachine@users.noreply.github.com>

x-pack/plugins/alerting/server/alert/create_alert_factory.ts

@@ -156,8 +156,6 @@ export function createAlertFactory<
             autoRecoverAlerts,
             // flappingSettings.enabled is false, as we only want to use this function to get the recovered alerts
             flappingSettings: DISABLE_FLAPPING_SETTINGS,
-            // no maintenance window IDs are passed as we only want to use this function to get recovered alerts
-            maintenanceWindowIds: [],
           });
           return Object.keys(currentRecoveredAlerts ?? {}).map(
             (alertId: string) => currentRecoveredAlerts[alertId]