[COMMON] Fix 'trap RETURN' and $BASHPID bashisms

pointed out by checkbashisms.

Issue-ID: OOM-2643
Signed-off-by: guillaume.lambert <guillaume.lambert@orange.com>
Change-Id: I19e7f50d5a98087d59cbe99778bee1a5f7a3a27c
diff --git a/kubernetes/sdnc/components/sdnc-prom/resources/bin/ensureSdncActive.sh b/kubernetes/sdnc/components/sdnc-prom/resources/bin/ensureSdncActive.sh
index 099103c..d92a104 100755
--- a/kubernetes/sdnc/components/sdnc-prom/resources/bin/ensureSdncActive.sh
+++ b/kubernetes/sdnc/components/sdnc-prom/resources/bin/ensureSdncActive.sh
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/sh
 
 {{/*
 # Copyright © 2018 Amdocs
@@ -33,8 +33,8 @@
     debugLog "Currently running sdnc and dns failover"
     return
   fi
-  trap "rm -f ${lockFile}" INT TERM RETURN
-  echo $BASHPID > ${lockFile}
+  trap "rm -f ${lockFile}" INT TERM EXIT
+  echo $$ > ${lockFile}
 
   # perform takeover
   debugLog "Started executing sdnc.failover for $SITE_NAME"