When performing DHCP-less deployments, the agent can start and
discover more than one configuration drive present on a host.
For example, a host was previously deployed using Ironic, and
is now being re-deployed again.
If Glean was present in the ramdisk, the glean-early.sh would end
mounting the folder based upon label.
If cloud-init, somehow is still in the ramdisk, the other folder
could somehow get mounted.
This patch, which is intended to be backportable, causes the agent
to unmount any configuration drive folders, mount the most likely
candidate based upon device type, partition, and overall state of
the machine, and then utilize that configuration, if present,
to re-configure and reload networking.
Thus allowing dhcp-less re-deployments to be fixed without
forcing any breaking changes.
It should also be noted that this fix was generated in concert
with an additional tempest test case, because this overall failure
case needed to be reproduced to ensure we had a workable non-breaking
path forward.
Closes-Bug: 2032377
Change-Id: I9a3b3dbb9ca98771ce2decf893eba7a4c1890eee
33f01fa3c2