conf: Deprecate 'allow_same_net_traffic'

Since I67556f1 removed the use of this flag in the libvirt port filter,
the only remaining use of this option is in nova-network. As a result,
we can deprecate this like nova-network itself.

Change-Id: I6e84862110d9597d8621a95f93e6c675f0ce7842
Implements: blueprint centralize-config-options-pike

nova/conf/network.py

@@ -1142,6 +1142,11 @@ Related options:
 """),
     cfg.BoolOpt('allow_same_net_traffic',
         default=True,
+        deprecated_for_removal=True,
+        deprecated_since='16.0.0',
+        deprecated_reason="""
+nova-network is deprecated, as are any related configuration options.
+""",
         help="""
 Determine whether to allow network traffic from same network.
 

releasenotes/notes/deprecate-more-nova-network-opts-a9f87c79f7d26438.yaml

@@ -43,3 +43,4 @@ deprecations:
     - ``public_interface``
     - ``routing_source_ip``
     - ``use_ipv6``
+    - ``allow_same_net_traffic``