azure pipeline: replace ubuntu-20.04 with 24.04
    
    Azure is deprecating the Ubuntu-20.04 Apr 15th, see announcement
    https://devblogs.microsoft.com/devops/upcoming-updates-for-azure-pipelines-agents-images/#ubuntu
    
    With the Ubuntu 24.04 image, we need to change permissions of /etc/shadow
    in order to allow sudo commands.
    
    Signed-off-by: Florence Blanc-Renaud <flo@redhat.com>
    Reviewed-By: Rafael Guterres Jeffman <rjeffman@redhat.com>