Instance create API can set pool_name to default if it is not provided

[askfongjojo]

The API does not complain when user specifies external_ips without a pool name:

  "external_ips": [
    {
      "type": "ephemeral"
    }
  ],

The instance doesn't get an external IP in this case. However, user doesn't have permission to list the ip pool names. They will not know what to specify there. The API should probably set the pool_name to default when it is not specified.

[askfongjojo]

With the latest IP pool design, this requested change is no longer desirable.