CI: proper pipeline fix?

Signed-off-by: Raphael Defosseux <raphael.defosseux@eurecom.fr>

ci-scripts/Jenkinsfile-gitlab

@@ -57,8 +57,8 @@ pipeline {
 
                     echo '\u2705 \u001B[32mVerify Parameters\u001B[0m'
                     def allParametersPresent = true
-                    if (${TESTPLATFORM_OWNER} != null) {
-                        echo "Platform is ${TESTPLATFORM_OWNER}"
+                    if (env.TESTPLATFORM_OWNER) {
+                        echo "Platform is ${env.TESTPLATFORM_OWNER}"
                     }
 
                     if (params.RedHatRemoteServer == null) {