Fix IFC direct upload callback failing on non-standard store paths

attachment_id_from_key used a regex anchored to `uploads/` which does
not match store paths on SaaS instances where the store_dir is
overridden with an instance-specific prefix (e.g. instance_qa_bim/...).

https://community.openproject.org/projects/STB/work_packages/STB-80/activity

modules/bim/app/controllers/bim/ifc_models/ifc_models_controller.rb

@@ -78,7 +78,7 @@ module Bim
       end
 
       def direct_upload_finished # rubocop:disable Metrics/AbcSize,Metrics/PerceivedComplexity
-        attachment_id = attachment_id_from_key(request.params[:key])
+        attachment_id = session[:pending_ifc_model_attachment_id]
         unless callback_context_valid?(attachment_id)
           fail_direct_upload
           return
@@ -264,10 +264,6 @@ module Bim
         actual_payload == expected_payload
       end
 
-      def attachment_id_from_key(key)
-        key.to_s.match(%r{\Auploads/[^/]+/file/(\d+)/[^/]+\z})&.captures&.first
-      end
-
       def fail_direct_upload
         flash[:error] = t("bim.error_direct_upload_failed")
         redirect_to action: :new