The glance-api-paste.ini and glance-registry-paste.ini configuration
files provided as part of the glance packages should be used; drop
charm templates and associated code paths.
This was required in early OpenStack versions where keystone auth
credentials where rendered into the paste ini file.
Existing deployments will go through a upgrade step to replace the
previously provided paste files from the charm with those provided
by the glance-api and glance-registry packages.
Change-Id: I016b8cb7823b98e8dffa91b3b427ed88a7b619bc
a8f380b4cf