Avoid failure in case no port-forwards are present.
Without || true the result will be
ps aux
grep port-forw
grep -v grep
awk '{print $2}'
xargs --no-run-if-empty kill -9
kill: (15338): No such process

and the pipeline will forcefully stop.

Change-Id: I0b377e406567dc2dc154eed21216aa5b3f1ca8b1
diff --git a/jjb/pipeline/voltha/voltha-2.7/bbsim-tests.groovy b/jjb/pipeline/voltha/voltha-2.7/bbsim-tests.groovy
index 41720cd..c72c0f9 100644
--- a/jjb/pipeline/voltha/voltha-2.7/bbsim-tests.groovy
+++ b/jjb/pipeline/voltha/voltha-2.7/bbsim-tests.groovy
@@ -129,7 +129,7 @@
       // remove port-forwarding
       sh """
         # remove orphaned port-forward from different namespaces
-        ps aux | grep port-forw | grep -v grep | awk '{print \$2}' | xargs --no-run-if-empty kill -9
+        ps aux | grep port-forw | grep -v grep | awk '{print \$2}' | xargs --no-run-if-empty kill -9 || true
       """
       // collect pod details
       get_pods_info("$WORKSPACE/${name}")