mantle/openstack: stop using boot-from-volume

[mnaser]

Since Mantle seems to upload QCOW2 images, when using boot from
volume, it leaves a huge load on the remote control plane due
to the fact that the image needs to be converted from QCOW2 into
RAW and then booted.

The reason why this was initially changed was because boots
were taking a long time, but now OpenStack has a download-direct
from the storage backend which will do a distributed pull that
would be way faster than download-on-convert on a single system.

[openshift-ci]

Hi @mnaser. Thanks for your PR.

I'm waiting for a coreos member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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[mnaser]

@dustymabe I hope you're doing well, this is pretty important to add please. It's causing control plane issues and in newer version of OpenStack, conversion can be disabled (which we plan to do) which would make these hard fail.

Thank you.

[dustymabe]

@dustymabe I hope you're doing well, this is pretty important to add please. It's causing control plane issues and in newer version of OpenStack, conversion can be disabled (which we plan to do) which would make these hard fail.

Hey @mnaser - good to hear from you (and hope you are doing well)!

Of course, sounds good.

[dustymabe]

LGTM

[jlebon]

Thanks for the patch @mnaser!