Removed automatic adding of NS routes

Removed automatic adding of NS routes

With openconnect version 9.01 include-split was modified, in a way that
a announced route with netwask 0.0.0.0 will leverage env variable `CISCO_SPLIT_INC`.

Entries inside `CISCO_SPLIT_INC`, always causes that routes to the NS
`INTERNAL_IP4_DNS` are created.

This commit, removes that NS routes are automatically are added.

The same mechanism applies to IP6 as well, which uses
env variable `CISCO_IPV6_SPLIT_INC`

Resolves #38. Alignment with behaviour of NetworkManager openconnect
see [1].

[1] https://gitlab.gnome.org/GNOME/NetworkManager-openconnect/-/blob/main/src/nm-openconnect-service-openconnect-helper.c

Signed-off-by: Heiko Schabert <heiko.schabert@siemens.com>