Raise qemu-img memory limit to 2 GiB
Raise qemu-img memory limit to 2 GiB

The current value is insufficient for modern images. A similar change to IPA:
https://review.opendev.org/c/openstack/ironic-python-agent/+/778035

Change-Id: Ia1535b375d2cec467011c7456da84b5811ba48dd

openstack/ironic-lib