Update env for ps +x in build

Change-Id: I6242827c3a291a7f3e6cc435b24f5f6d0aed969d
diff --git a/releng/Jenkinsfile.groovy b/releng/Jenkinsfile.groovy
index 6cba438..edd4379 100644
--- a/releng/Jenkinsfile.groovy
+++ b/releng/Jenkinsfile.groovy
@@ -202,7 +202,9 @@
   sh "dd if=/dev/zero of=file.txt count=100 bs=1048576" // 1048576 bytes = 1Mb
   sh "rm file.txt"
 
-  sh "ps x"
+  container(BUILD_CONTAINER_NAME) {
+    sh "ps x"
+  }
 }
 
 def deploy(String mode, String arg = "M0") {