Fix glance configuration for ceilometer

Modify /etc/glance/glance-api.conf, not /etc/ceilometer/ceilometer.conf.

Change-Id: I3725a6578fcad6c49b2fc1cd9495d391157e714b
Closes-Bug: #1269657
backport: havana
(cherry picked from commit 54a79d7b5292c179837542e5cb570ac3ab529b9e)