Do not direclty define global var extraVarsYaml for test-cookiecutter job

This parameter is using inside one method and should not be declared.

Change-Id: Ibf8d54951a0a2fb4dfc593277b5d5e3923f40da6
diff --git a/test-cookiecutter-reclass.groovy b/test-cookiecutter-reclass.groovy
index d256b94..8ca2573 100644
--- a/test-cookiecutter-reclass.groovy
+++ b/test-cookiecutter-reclass.groovy
@@ -17,7 +17,7 @@
 git = new com.mirantis.mk.Git()
 python = new com.mirantis.mk.Python()
 
-def extraVarsYAML = env.EXTRA_VARIABLES_YAML.trim() ?: ''
+extraVarsYAML = env.EXTRA_VARIABLES_YAML.trim() ?: ''
 if (extraVarsYAML) {
     common.mergeEnv(env, extraVarsYAML)
 }