MT#55283 el: don't fork to background

Reported in #1896

Change-Id: I58d09ef930c8fa55efa5592ff746a65270dea68b
(cherry picked from commit aca2433bbd)
(cherry picked from commit a753771c32)

el/rtpengine.service

@@ -3,7 +3,7 @@ Description=NGCP RTP/media Proxy Daemon
 After=network-online.target
 
 [Service]
-Type=forking
+Type=notify
 Environment=CFG_FILE=/etc/rtpengine/rtpengine.conf
 EnvironmentFile=/etc/sysconfig/rtpengine
 User=ngcp-rtpengine
@@ -13,7 +13,7 @@ CapabilityBoundingSet=CAP_NET_ADMIN CAP_SYS_NICE
 LimitNOFILE=150000
 RuntimeDirectory=rtpengine
 PIDFile=/run/rtpengine/rtpengine.pid
-ExecStart=/usr/bin/rtpengine --config-file=${CFG_FILE} --pidfile=${PID_FILE}
+ExecStart=/usr/bin/rtpengine --config-file=${CFG_FILE} --pidfile=${PID_FILE} -f
 RestartSec=3s
 TimeoutSec=15s
 Restart=on-failure