gate: stop getting VERSION_ID

This variable is not used at all in our testing and it's not always
available in all operating systems (i.e. buster)

Change-Id: I43146f1e6d70add9f4c175d5b86987d348e70073

scripts/scripts-library.sh

@@ -61,7 +61,6 @@ function determine_distro {
     source /etc/os-release 2>/dev/null
     export DISTRO_ID="${ID}"
     export DISTRO_NAME="${NAME}"
-    export DISTRO_VERSION_ID="${VERSION_ID}"
 }
 
 function ssh_key_create {