Fixed credentials issue in system reclass test job

Change-Id: I67dd3831c56002b1a18a829582bb1aad253d01c9
diff --git a/test-system-reclass-pipeline.groovy b/test-system-reclass-pipeline.groovy
index 4382204..27106fe 100644
--- a/test-system-reclass-pipeline.groovy
+++ b/test-system-reclass-pipeline.groovy
@@ -31,7 +31,7 @@
       if (gerritRef) {
         // job is triggered by Gerrit
         // test if change aren't already merged
-        def gerritChange = gerrit.getGerritChange(GERRIT_NAME, GERRIT_HOST, GERRIT_CHANGE_NUMBER, CREDENTIALS_ID)
+        def gerritChange = gerrit.getGerritChange(GERRIT_NAME, GERRIT_HOST, GERRIT_CHANGE_NUMBER, gerritCredentials)
         merged = gerritChange.status == "MERGED"
         if(!merged){
           checkouted = gerrit.gerritPatchsetCheckout ([