devstack: Fix dib image location
devstack: Fix dib image location

We're building astara.qcow2 but pointing glance to akanda.qcow2.

This fixes it and should fix the dsvm-src jobs.

Change-Id: I2e87e8bdcc3ad17d8689cd74e9697dc371849006

openstack/akanda-rug,stackforge/akanda-rug,openstack/akanda-rug,stackforge/akanda-rug