sending stderr of cta-admin to /dev/null for the client_ar.sh test script.

continuousintegration/orchestration/tests/client_helper.sh

@@ -20,7 +20,7 @@ die() {
 }
 
 admin_cta() {
-  KRB5CCNAME=/tmp/${CTAADMIN_USER}/krb5cc_0 cta-admin $@
+  KRB5CCNAME=/tmp/${CTAADMIN_USER}/krb5cc_0 cta-admin $@ 2>/dev/null
 }
 
 admin_klist() {