The default incoming chunk size is controlled by session negotiator,
make sure to co-locate the tuneable value there and remove deprecated
constructors for both NetconfChunkAggregator and
AbstractNetconfSessionNegotiator.
Change-Id: Iab489e35e18905c33a747a52c1698ece4e51d3ef Signed-off-by: Robert Varga <robert.varga@pantheon.tech>