[ResponseOps][Alerts] Problem filtering alerts in actions portion of the rules form

[adcoelho]

Describe the bug:

When defining actions for a rule the filtering area If alert matches a query is not working as expected. We should be able to define either a filter or a KQL query but the form always expects a KQL query. This makes the filters useless/redundant.

Steps to reproduce:

1. Go to Rules and try creating a new rule of any type
2. Add an action to the rule
3. Check the option If alert matches a query
4. Observe that the error A custom query is required. is displayed before the user interacts with this form section.
5. Click the plus sign to open the Add a filter tooltip (AlertsSearchBar component)
6. Add a filter and click Save
7. Observe that the error A custom query is required. is still displayed, preventing the form from being submitted.

The form can only be submitted if we add a query to the Filter alerts using KQL syntax text box.

Expected behavior:

1. The error A custom query is required. shouldn't be displayed before the user interacts with the form.
2. Adding a filter using the tooltip should be an alternative to the KQL option. We should be able to submit the form if either of these is defined.

Screenshots:

Form displaying the error by default

Form with a filter defined but still displaying an error.

Form without errors when a filter and a query are defined.

[elasticmachine]

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