Update glance.conf for performance of storage

Issue: recent fixes related to performance of storage with
    are not available in SM installation.
Fix: Added configuration changes to glance.conf while provisioning
    contrail-storage.

Testing: Installed contrail-storage and verified glance.conf has those
    required changes.

Change-Id: Idab0adc1f7a38fed5f0a974942e0da5783a36e01
Closes-Bug: #1384782