MT#63358 readonly prodile_id for GET /api/subscribers

profile_id field seems mandatory for admin UI.
bringing it back as readonly.

Change-Id: I40d0842b83b54b37e80a469da4234c6feddcdaba
(cherry picked from commit 4c7b7891c8)

lib/NGCP/Panel/Form/Subscriber/SubscriberSubAdminAPI.pm

@@ -98,8 +98,6 @@ has_field 'password' => (
     },
 );
 
-
-
 has_field 'administrative' => (
     type => 'Boolean',
     label => 'Administrative',
@@ -143,6 +141,17 @@ has_field 'customer_id' => (
     },
 );
 
+has_field 'profile' => (
+    type => '+NGCP::Panel::Field::SubscriberProfile',
+    label => 'Subscriber Profile',
+    validate_when_empty => 0,
+    readonly => 1,
+    element_attr => {
+        rel => ['tooltip'],
+        title => ['The profile defining the actual feature set for this subscriber.'],
+    },
+);
+
 has_field 'display_name' => (
     type => 'Text',
     label => 'Display Name',