router: adding "data-server" dns entry in /etc/hosts (#4319)

The DNS entry "data-server" was not added in /etc/hosts.

Since the VR is now considered as a "dhcpsrvr" (?), we need to apply this commit to add this DNS entry.
/etc/hosts is fully rewritten by this script.

Fixes: #4308
(cherry picked from commit dc65f31)
Signed-off-by: Rohit Yadav <rohit.yadav@shapeblue.com>

Author: Lucasgranet

systemvm/debian/opt/cloud/bin/cs/CsDhcp.py

@@ -158,7 +158,7 @@ def preseed(self):
         self.add_host("::1", "localhost ip6-localhost ip6-loopback")
         self.add_host("ff02::1", "ip6-allnodes")
         self.add_host("ff02::2", "ip6-allrouters")
-        if self.config.is_router():
+        if self.config.is_router() or self.config.is_dhcp():
             self.add_host(self.config.address().get_guest_ip(), "%s data-server" % CsHelper.get_hostname())
 
     def write_hosts(self):