Fix gating job for cookiecutter templates and reclass-system

 * Fix passing of GERRIT_* params, to be able correctly process
   each of jobs in downstream call's

Related-Bug: PROD-23343 (PROD:23343)

Change-Id: I1b3a4610ec91f1d53a4043d282f1b112860c057a
diff --git a/test-cookiecutter-reclass.groovy b/test-cookiecutter-reclass.groovy
index 6813be9..598ab01 100644
--- a/test-cookiecutter-reclass.groovy
+++ b/test-cookiecutter-reclass.groovy
@@ -17,6 +17,10 @@
 git = new com.mirantis.mk.Git()
 python = new com.mirantis.mk.Python()
 
+if (env.EXTRA) {
+    common.mergeEnv(env, env.EXTRA)
+}
+
 slaveNode = env.SLAVE_NODE ?: 'docker'
 checkIncludeOrder = env.CHECK_INCLUDE_ORDER ?: false