Handle improperly defined Watcher Logging Action text parameter.

[cjcenizal]

Closes #60128

Release note

Improperly defined Watcher Logging Action text parameters will now be handled elegantly by Kibana instead of causing Kibana to crash.

Steps to test

Create an Advanced Watch with this body:

{
  "trigger": {
    "schedule": {
      "interval": "5m"
    }
  },
  "input": {
    "simple": {
      "foo": "bar"
    }
  },
  "actions": {
    "log": {
      "logging": {
        "text": {
          "inline": ""
        }
      }
    }
  }
}

This request would original fail with a browser dev tools error, because the code didn't expect logging.text to be defined as anything but a string. Now the request will succeed and the API will replace the invalid logging.text configuration with a default:

{
  "trigger" : {
    "schedule" : {
      "interval" : "5m"
    }
  },
  "input" : {
    "simple" : {
      "foo" : "bar"
    }
  },
  "condition" : {
    "always" : { }
  },
  "actions" : {
    "log" : {
      "logging" : {
        "level" : "info",
        "text" : {
          "source" : "",
          "lang" : "mustache"
        }
      }
    }
  },
  "metadata" : {
    "xpack" : {
      "type" : "json"
    }
  }
}

[elasticmachine]

Pinging @elastic/es-ui (Team:Elasticsearch UI)

[kibanamachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request
• Commit: 3bfedd7

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream

[alisonelizabeth]

Code LGTM. Tested locally. Thanks for fixing this @cjcenizal!