Fix up user configuration in install image
Fix up user configuration in install image

We use cloud-init to create the initial user on the target system.
Ensure the password login works, that it has a shell (/bin/bash)
and sudo privs via group admin.

Signed-off-by: Ryan Harper <7c8ea25f69f5166c51151e84bf5db678c2384828@canonical.com>

CanonicalLtd/subiquity,CanonicalLtd/subiquity