Fix dependency proxy invalid method name

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

ee/app/controllers/groups/dependency_proxies_controller.rb

@@ -7,7 +7,7 @@ module Groups
 
     def show
       @blobs_count = group.dependency_proxy_blobs.count
-      @blobs_total_size = group.dependency_proxy_blobs.size_sum
+      @blobs_total_size = group.dependency_proxy_blobs.total_size
     end
 
     def update

ee/app/views/groups/dependency_proxies/_url.html.haml

@@ -4,4 +4,4 @@
   = text_field_tag :url, "#{group_url(@group)}/dependency_proxy/containers", class: 'js-dependency-proxy-url form-control', readonly: true
 
 .help-block.prepend-top-5
-  Contains #{@blobs_count} blobs of images (#{number_to_human_size(@blobs_total_size)})
+  Contains #{@blobs_count} blobs of images (#{number_to_human_size(@blobs_total_size)})
\ No newline at end of file

ee/spec/features/groups/dependency_proxy_spec.rb

@@ -75,4 +75,4 @@ describe 'Group Dependency Proxy' do
       end
     end
   end
-end
+end
\ No newline at end of file