Use model translations in adjustment_reason view

The AdjustmentReason model is used in translations in the index view.

backend/app/views/spree/admin/adjustment_reasons/index.html.erb

@@ -1,7 +1,7 @@
 <%= render partial: 'spree/admin/shared/configuration_menu' %>
 
 <% content_for :page_title do %>
- <%= Spree.t(:adjustment_reasons) %>
+ <%= Spree::AdjustmentReason.model_name.human(count: :other) %>
 <% end %>
 
 <% content_for :page_actions do %>
@@ -44,7 +44,7 @@
  </table>
 <% else %>
  <div class="alpha twelve columns no-objects-found">
- <%= Spree.t(:no_resource_found, resource: I18n.t(:other, scope: 'activerecord.models.spree/adjustment_reason')) %>,
+ <%= Spree.t(:no_resource_found, resource: Spree::AdjustmentReason.model_name.human(count: :other)) %>,
  <%= link_to Spree.t(:add_one), new_object_url %>!
  </div>
 <% end %>