main: Respect config start_native_transport option
main: Respect config start_native_transport option

There's such an option, and it's not taken into account
on scylla start. There's a symmetrical start_rpc one, which
is, so make both act similarly.

The default value for the option is true, so default set-ups
will not get broken.

Signed-off-by: Pavel Emelyanov <c9a32589e048e044184536f7ac71ef92fe82df3e@scylladb.com>
Message-Id: <20200310140518.29410-1-c9a32589e048e044184536f7ac71ef92fe82df3e@scylladb.com>

avikivity/scylla,avikivity/scylla,scylladb/scylla,scylladb/scylla,scylladb/scylla,avikivity/scylla,scylladb/scylla