Since we install the free version of Nvidia drivers on all systems
except those with a V100, such systems running Focal will fail
deployment since nvidia-driver-470-server-open does not exist.
This change ensures any attempts to download 470 drivers only
search for nvidia-driver-470-server.
Per discussion in https://warthogs.atlassian.net/browse/NVDGX-314
(regarding LP: #2025614), we determined that fabricmanager is
automatically started on compatible systems at install time,
so this enable call is unnecessary.
Added || true to "ipmitool sel clear" so MAAS deployment can continue if that command fails
On Hinyari, "ipmitool sel clear" will exit with code 1 and output "Unable to clear SEL: Unspecified error",
which causes the entire deployment to fail.
Since this is not a critical step of the deployment, this should not happen. This change allows the deployment
to continue while still printing the error message to the console.