Replace duplicate random generator with common function

salt/common/tools/sbin/so-common

@@ -135,3 +135,8 @@ fail() {
   echo "Exiting."
   exit 1
 }
+
+get_random_value() {
+  length=${1:-20}
+  head -c 5000 /dev/urandom | tr -dc 'a-zA-Z0-9' | fold -w $length | head -n 1
+}