Drop lib/neutron module

Module lib/neutron was introduced long time ago as new module to deploy
neutron. It was intended to replace old lib/neutron-legacy module. But
since very long time it wasn't really finished and used by anyone and
lib/neutron-legacy is defacto standard module used by everyone to deploy
neutron with devstack.
In [1] unfinished lib/neutron was deprecated and now it's time to remove
it from the devstack code.

This patch also renames old "lib/neutron-legacy" module to be
"lib/neutron" now.

Previously "old" lib/neutron-legacy module was accepting neutron
services names wit "q-" prefix and "new" lib/neutron module was accepting
services with "neutron-" prefix. Now, as there is only one module it
accepts both prefixes.
For historical reasons and to be consistent with old lib/neutron-legacy
which was widely used everywhere, services will be named with "q-"
prefix but both prefixes will be accepted to enable or disable services.

This patch also moves _configure_neutron_service function to be called
at the end of the "configure_neutron" after all agents and service
plugins are already configured.

[1] https://review.opendev.org/c/openstack/devstack/+/823653

Related-bug: #1996748

Change-Id: Ibf1c8b2ee6b6618f77cd8486e9c687993d7cb4a0
diff --git a/lib/neutron_plugins/ml2 b/lib/neutron_plugins/ml2
index 46edacd..c2e78c6 100644
--- a/lib/neutron_plugins/ml2
+++ b/lib/neutron_plugins/ml2
@@ -67,7 +67,7 @@
     Q_PLUGIN_CLASS="ml2"
     # The ML2 plugin delegates L3 routing/NAT functionality to
     # the L3 service plugin which must therefore be specified.
-    _neutron_service_plugin_class_add $ML2_L3_PLUGIN
+    neutron_service_plugin_class_add $ML2_L3_PLUGIN
 }
 
 function neutron_plugin_configure_service {