Glance has a facility lazy loading for legacy images which will be called
on get/list api calls to add store information in image's location metadata
based on location URL of image. Even if admin decides to change the store
names in glance-api.conf same will also be updated in location metadata
for all images related to that particular store. Current implementation of
legacy image performs this operation on each get/list call as location metadata
is not getting updated in database or it doesn't handle to perform store name
check in glance-api.conf.
1. Save updated location metadata information in database permenantly
2. Add logic to perform lazy loading only if store information is not present
in location metadata or store present in location metadata is not defined in
glance's enbaled_backends configuration option.
(cherry picked from commit