Don't show flashes until everything else is done.

Mario reported that it was showing before the loading spinner had gone.
Technically the loading spinner doesn't hide until after the reflex is finished, but hopefully this is close enough.

app/reflexes/products_reflex.rb

@@ -39,12 +39,12 @@ class ProductsReflex < ApplicationReflex
 
     if product_set.save
       flash[:success] = I18n.t('admin.products_v3.bulk_update.success')
-      broadcast_admin_flashes
     elsif product_set.errors.present?
       @error_counts = { saved: product_set.saved_count, invalid: product_set.invalid.count }
     end
 
     render_products_form
+    broadcast_admin_flashes if flash.any?
   end
 
   private