Ubuntu related changes

.gitlab-ci.yml

CICD/plays/allnodes.yml

CICD/vars/u18packages.yml

CICD/vars/u20packages.yml

CICD/vars/vars_ubuntu18.yml

CICD/vars/vars_ubuntu20.yml

roles/buildLustreClient/tasks/main.yml

roles/extra_packages/tasks/main.yml

roles/ldapclient/tasks/configLdapClient.yml

roles/mellanox_drivers/tasks/main.yml

roles/nfs-client/tasks/mountFileSystem.yml

roles/pam_sshd/tasks/main.yml

roles/pam_sshd/templates/loginnodes_sshd.j2

roles/pam_sshd/templates/loginnodes_sshd_centos.j2

roles/pam_sshd/templates/loginnodes_sshd_ubuntu.j2

roles/telegraf/tasks/main.yml

roles/vncserver/tasks/main.yml