Use spree_user instead of spree_current_user

Devise utilizes spree_user scope when executing after_sign_in_path.
This is an important distinction when storing the user location as the
user would not be redirected as expected if we use spree_current_user.

Co-Authored-By: Elia Schito <elia@schito.me>

lib/spree/authentication_helpers.rb

@@ -42,11 +42,11 @@ def storable_spree_user_location?
     end
 
     def store_spree_user_location!
-      store_location_for(:spree_current_user, request.fullpath)
+      store_location_for(:spree_user, request.fullpath)
     end
 
     def stored_spree_user_location_or(fallback_location)
-      stored_location_for(:spree_current_user) || fallback_location
+      stored_location_for(:spree_user) || fallback_location
     end
   end
 end