Stop copying directly-connected routes to the main table.

For a long time we have thought that copying directly-connected
routes to the main table was necessary to add gatewayed routes
to other routing tables. However, this is not necessary when the
directly-connected routes are properly created with "scope link"
as we do in http://ag/513100 .

Delete the copying code, but keep dumping the main table in
bugreports, so we can see if third-party code such as RIL
daemons is putting anything in it.

Change-Id: Iddd531daaf9881ffd82f0a4b4f6cc857ce8788fd