UI Bug in provisioned opsgenie alerts

[sidewinder12s]

On Provisioned Contact Points for OpsGenie, the UI appears to have a bug where it is requiring the OpsGenie URL be filled in, even though it is defaulting to the correct URL on the backend (we did not provide a URL in our Terraform config for the contact point, relying on the default).

It appears to only surface when you are using the Test button.

Steps to reproduce:

1. Provision an OpsGenie Contact Point without the Alert URL set through the API
2. Click Test, run a test
3. Close the test frame
4. Now you can no longer click test as it is erroring out on the missing alert URL

Looks like the default is being set here:

alerting/receivers/opsgenie/config.go

Lines 64 to 66 in 2dda1c6

	if raw.APIUrl == "" {
	raw.APIUrl = DefaultAlertsURL
	}

The UI should fill this in on the user facing side as well.