[ResponseOps] warnings/errors when deleting/disabling rules with no active alerts

[pmuellr]

When you attempt to delete a rule that has not generated alerts, you'll get the following messages logged in Kibana:

ERROR - Error marking ruleIds <id> as untracked - No active alerts matched the query
WARN  - rulesClient.disable('<id>') - Could not write untrack events - No active alerts matched the query

This isn't really an error, nor something we need to warn about. AFAIK. It's just that the rule had no alerts.

I think we can change these to DEBUG instead ...

[elasticmachine]

Pinging @elastic/response-ops (Team:ResponseOps)

[mikecote]

cc @cnasikas