update ec2 instance image to latest ubuntu LTS

[aagbsn]

/tf/modules/ec2/main.tf: name = "/aws/service/canonical/ubuntu/server/22.04/stable/current/amd64/hvm/ebs-gp2/ami-id"

this will be EOL in Jun 2027

[aagbsn]

note: the ansible playbook for deployment notices that systemd-resolved is missing in 22.04 (present in 24.04)

[aagbsn]

#319

[aagbsn]

also the backendproxy instance:
#320