Removed 'Networking' section

Old (0.4.x style) section, containing networking parameters of environment, is never processed
by the engine, so it has been removed from the environment generation logic.

New (0.5-compatible) block of network setting will be added at murano-api side.

This is part of Advanced Networking commit series, yet is independent from all others.

Change-Id: I34ccee96a22d598de9693205b064b0d1bd118ded
Partial-bug: #1308921
Merge "Removed 'Networking' section"