Give caas azimuth user sudo

[sjpb]

For the caas environment:

• The user's ssh key is only injected for the azimuth user (not rocky)
• The deploy key is only injected for the rocky user
• The azimuth user can now login to the control node
• The azimuth user has passwordless sudo on all nodes
• The azimuth user is permitted to ssh into compute nodes even without jobs running

Note that:

• The azimuth user is setup via the basic_users role instead of cloud-init as ssh keys need to be created on a shared $HOME and propagated across the cluster.
• To allow the azimuth user to login to the control node, the default shell logic in the basic_users role is overriden and NFS configuration is modified so the control node has /home mounted.

[sjpb]

Checks using Azimuth user:

• can ssh into compute and sudo
• can ssh into control and sudo
• can sudo on login

[sd109]

LGTM

It would be good to also update the Azimuth user docs here to reflect these changes.

[sjpb]

Redone checks after merge from main changed image.