Check that etc/resolv.conf.ORIG exists before edit

In RHEL 8.4, /etc/resolv.conf is not present by default.
As such, removing the nameservers will fail because
etc/resolv.conf.ORIG never gets created.

This patch makes the nameserver edit only if the
etc/resolv.conf.ORIG file exists.

Change-Id: I2178996d899ffe43e11bfeb512e4fcaa941b8410
(cherry picked from commit 5c4be3e158)

elements/remove-resolvconf/cleanup.d/90-remove-resolvconf

@@ -11,4 +11,6 @@ set -o pipefail
 # NOTE: This relies on the fact the DIB copies the original resolv.conf and
 # during the finalise_base function in img-functions (in DIB) copies the old
 # one back in place after the build process completes.
-sudo sed -i '/nameserver/d' $TARGET_ROOT/etc/resolv.conf.ORIG
+if [ -f $TARGET_ROOT/etc/resolv.conf.ORIG ] ; then
+    sudo sed -i '/nameserver/d' $TARGET_ROOT/etc/resolv.conf.ORIG
+fi