Fix bug when url is not set for stack not using the calculated field from the backend (#2352)

Author: nachogiljaldo

internal/resources/cloud/resource_cloud_stack.go

@@ -104,6 +104,7 @@ Required access policy scopes:
 			"url": {
 				Type:        schema.TypeString,
 				Optional:    true,
+				Computed:    true,
 				Description: "Custom URL for the Grafana instance. Must have a CNAME setup to point to `.grafana.net` before creating the stack",
 				DiffSuppressFunc: func(k, oldValue, newValue string, d *schema.ResourceData) bool {
 					return oldValue == newValue ||