Filtering alert list by unused action type loads "create your first alert"

[peterschretlen]

Found on kibana master 141acf9

If you filter the alert listing by an action type that is not used, the "create your first alert" page loads:

Expected: you should get an empty list, not the "create your first alert" page, and the search bar and filters should remain visible.

[elasticmachine]

Pinging @elastic/kibana-alerting-services (Team:Alerting Services)

[peterschretlen]

Noticed that this occurs with any filter operation that creates an empty list:

• Filter by action type that is unused
• Filter by alert type that is unused
• Enter a query in the search bar that returns no results