Remove Neutron core static example configuration files

Remove Neutron core static example configuration files

Oslo config generator was introduced in patch [1] to
automatically generate the sample Neutron core configuration
files.

This patch removes the static example configuration files from
the repository as they are now redundant.

[1] https://review.openstack.org/#/c/204206/

DocImpact

Change-Id: Ic7ae2e038b5bd7b215c65c9c565bfe31ef551520
Partially-Implements: blueprint autogen-neutron-conf-file
Closes-bug: #1199963
Depends-On: Ic37a16b6cf8eb92030649f1fc8b198738a8cc104