Change allocation count calculation

The API includes CurrentWriters and CurrentReaders in the
collection response, so this uses that instead of counting
WriteAllocs and ReadAllocs, which are not returned in the
collection.

The individual volume response doesn’t include CurrentWriters
and CurrentReaders but their absence doesn’t erase the values.

ui/app/models/volume.js

@@ -18,6 +18,14 @@ export default class Volume extends Model {
     return [...this.writeAllocations.toArray(), ...this.readAllocations.toArray()];
   }
 
+  @attr('number') currentWriters;
+  @attr('number') currentReaders;
+
+  @computed('currentWriters', 'currentReaders')
+  get allocationCount() {
+    return this.currentWriters + this.currentReaders;
+  }
+
   @attr('string') externalId;
   @attr() topologies;
   @attr('string') accessMode;

ui/app/templates/csi/volumes/index.hbs

@@ -62,7 +62,7 @@
                 ({{row.model.nodesHealthy}}/{{row.model.nodesExpected}})
               </td>
               <td data-test-volume-provider>{{row.model.provider}}</td>
-              <td data-test-volume-allocations>{{row.model.allocations.length}}</td>
+              <td data-test-volume-allocations>{{row.model.allocationCount}}</td>
             </tr>
           </t.body>
         </ListTable>

ui/mirage/serializers/csi-volume.js

@@ -23,7 +23,10 @@ export default ApplicationSerializer.extend({
 });
 
 function serializeVolumeFromArray(volume) {
+  volume.CurrentWriters = volume.WriteAllocs.length;
   delete volume.WriteAllocs;
+
+  volume.CurrentReaders = volume.ReadAllocs.length;
   delete volume.ReadAllocs;
 }