Fix default value

Author: kbatuigas

cloud-dataplane/cloud-dataplane.yaml

@@ -4978,9 +4978,9 @@ servers:
     url: 'https://{dataplane_api_url}.cloud.redpanda.com'
     variables:
       dataplane_api_url:
-        default: ""
+        default: "dataplane_api.url"
         description: |-
-          Find the Data Plane API base URL of a cluster by calling the Get Cluster endpoint of the Control Plane API. The dataplane_api.url field is returned in the response body. This field is required and there is no default value.<br><br>
+          Find the Data Plane API base URL of a cluster by calling the Get Cluster endpoint of the Control Plane API. The dataplane_api.url field is returned in the response body.<br><br>
           Example (Dedicated): "https://api-a4cb21.ck09mi9c4vs17hng9gig.fmc.prd.cloud.redpanda.com"<br>
           Example (BYOC): "https://api-a4cb21.ck09mi9c4vs17hng9gig.byoc.prd.cloud.redpanda.com"
 tags: