Kibana SLOs: use spaceID

[afharo]

When creating the SLOs against a custom space ID, I'm getting the following errors:

╷
│ Error: Provider produced inconsistent result after apply
│ 
│ When applying changes to elasticstack_kibana_slo.kibana_http_latency_slo, provider "provider[\"terraform.local/elastic/elasticstack\"]" produced an unexpected new value: Root resource was present, but now absent.
│ 
│ This is a bug in the provider, which should be reported in the provider's own issue tracker.
╵

This is caused because TF is correctly creating it in the indicated space, but retrieving it from the default one.

[tobio]

Thanks for taking the time fix this one up 👍