SKYH4-4521: Investigate dhcpv4 client for Italy v4 outage on 21/01/21
SKYH4-4521: Investigate dhcpv4 client for Italy v4 outage on 21/01/21

Reason for change:
This commit is to remove the service_wan.sh and related binaries as this is not required
any more. The dml function for dhcp renewal has been changed to prevent setting the
dhcp_client-renew sysevent.The dhcp renewal data model will use cms messaging mechanism
to communicate to the new skydhcpc client when a user ussues a dhcp force renewal command.
   At present the dhcp renew functionality through dmcli is not implemented but it would be
implemented with the opensource version of wan manager later.

Test Procedure:
1. Make sure that the old udhcpc client is running neither during startup nor when
   issuing the dhcp renew dmcli command.
2. Make sure that the service_wan.sh and service_wan binary is not running on startup,
   this could be verified by examining the OnBoardingLog.txt.0 and making sure that the
   log "Wan_init_start.." is not present.
2. Make sure there is no  changes to dns conf file resolve.conf after
   executing the dhcp renew command.
3. Make sure there is no changes in the following sys-events after
   executing the dhcp renew command.
4. Make sure that the Firewall is not restarted when executing the
   dhcp renew command.
Risks: low

Signed-off-by: Retheesh Sasidharan <7950f5ca45329bdf219af32633f623816587bc71@sky.uk>
(cherry picked from commit 2261b31874474d333ff12c0c6b9966a4a5fbab72)
Change-Id: I851e55e44a7b5ac7a94b3632797db650d74c162e

rdkcmf/rdkb-CcspPandM,rdkcmf/rdkb-CcspPandM,rdkcmf/rdkb-CcspPandM