SYSTEMD: Remove set -e to allow failure

'set -e' flag doesn't allow to fall back to 'return 0' when a command
fails. As installation/removal should not fail in most cases - 'set -e'
flag has been removed.

Below page recommends to be careful with 'set -e' usage:
https://www.debian.org/doc/debian-policy/ch-opersys.html#writing-the-scripts

Change-Id: If4439aaff66747bceabd3beb7e00ae12ce950e43
Signed-off-by: Galantsev, Dmitrii <dmitrii.galantsev@amd.com>

src/DEBIAN_postinst.in

@@ -1,7 +1,5 @@
 #!/bin/bash
 
-set -e
-
 # This will return 0 if an id is created and non-zero if
 # it already exists
 # https://www.debian.org/doc/debian-policy/ch-opersys.html#users-and-groups

src/DEBIAN_prerm.in

@@ -1,7 +1,5 @@
 #!/bin/bash
 
-set -e
-
 stop_rdc() {
     if [ -d /run/systemd/system ]; then
         #stop RDC if running
@@ -11,8 +9,9 @@ stop_rdc() {
 }
 
 rm_rdc_service() {
-    if [ -e /run/systemd/system ]; then
-       unlink /lib/systemd/system/rdc.service
+    local LINK=/lib/systemd/system/rdc.service
+    if [ -L $LINK ]; then
+       unlink $LINK
     fi
     return 0
 }

src/RPM_postun.in

@@ -9,8 +9,9 @@ stop_rdc() {
 }
 
 rm_rdc_service() {
-    if [ -e /run/systemd/system ]; then
-        unlink @DISTRO_ROOT@/rdc.service
+    local LINK=@DISTRO_ROOT@/rdc.service
+    if [ -L $LINK ]; then
+       unlink $LINK
     fi
     return 0
 }