[Logs UI] Creation of log threshold alerts with "matches phrase" comparator fails

[weltenwort]

Kibana version: master as of 25d143f

Problem description

Creating a log threshold alert with "matches phrase" as the condition fails.

The request sent by the browser is

{
  "params": {
    "count": {
      "value": 75,
      "comparator": "more than"
    },
    "criteria": [
      {
        "field": "message",
        "comparator": "matches phrase",
        "value": "apache"
      }
    ],
    "timeSize": 5,
    "timeUnit": "m"
  },
  "consumer": "logs",
  "alertTypeId": "logs.alert.document.count",
  "schedule": {
    "interval": "1m"
  },
  "actions": [
    {
      "id": "b0b0e6d8-572d-4cd2-afb8-9d21dad125df",
      "actionTypeId": ".server-log",
      "group": "logs.threshold.fired",
      "params": {
        "level": "info",
        "message": "{{#context.group}}{{context.group}} - {{/context.group}}{{context.matchingDocuments}} log entries have matched the following conditions: {{context.conditions}}"
      }
    }
  ],
  "tags": [],
  "name": "Test Log Alert"
}

The response is a 400 - Bad Request with the following message:

params invalid: [criteria.0.comparator]: types that failed validation:- [criteria.0.comparator.0]: expected value to equal [more than]- [criteria.0.comparator.1]: expected value to equal [less than]- [criteria.0.comparator.2]: expected value to equal [more than or equals]- [criteria.0.comparator.3]: expected value to equal [less than or equals]- [criteria.0.comparator.4]: expected value to equal [equals]- [criteria.0.comparator.5]: expected value to equal [does not equal]- [criteria.0.comparator.6]: expected value to equal [matches]- [criteria.0.comparator.7]: expected value to equal [does not match]

Steps to reproduce

1. Navigate to the Logs UI.
2. Open the "Create Alert" flyout.
3. Enter a name for the alert.
4. Change the alert condition to "MATCHES PHRASE".
   
5. Create the alert.
6. Observe the error message.

Context

The response looks like a kbn-config-schema validation error. My initial guess would be that the schema defined at

kibana/x-pack/plugins/infra/server/lib/alerting/log_threshold/register_log_threshold_alert_type.ts

Lines 50 to 59 in 25d143f

	comparator: schema.oneOf([
	schema.literal(Comparator.GT),
	schema.literal(Comparator.LT),
	schema.literal(Comparator.GT_OR_EQ),
	schema.literal(Comparator.LT_OR_EQ),
	schema.literal(Comparator.EQ),
	schema.literal(Comparator.NOT_EQ),
	schema.literal(Comparator.MATCH),
	schema.literal(Comparator.NOT_MATCH),
	]),

is incomplete.

[elasticmachine]

Pinging @elastic/logs-metrics-ui (Team:logs-metrics-ui)