Move back to using upstream upper-constraints

neutron has been added to the upper constraints file, which means we
can't install it from a tarball (pip gets upset when you try to
install from source while also attempting to specify a version in your
constraints). This commit replaces the reference to the tarball in the
openstack-projects part w/ a reference to neutron from pip.

We still install other OpenStack packages in the part from tarballs,
as the versions of those packages are not locked down in the
upper-constraints.

Change-Id: Id73fbc927c0b56ae6242f2abcaed7b6208f69a9e

snapcraft.yaml

@@ -419,7 +419,7 @@ parts:
       - libvirt
       - patches
     constraints:
-      - ${SNAPCRAFT_STAGE}/patches/upper-constraints.txt
+      - https://raw.githubusercontent.com/openstack/requirements/stable/stein/upper-constraints.txt
     source: http://tarballs.openstack.org/keystone/keystone-stable-stein.tar.gz
     python-packages:
       - libvirt-python
@@ -428,7 +428,7 @@ parts:
       - uwsgi
       - git+https://opendev.org/x/snap.openstack#egg=snap.openstack
       - http://tarballs.openstack.org/nova/nova-stable-stein.tar.gz
-      - http://tarballs.openstack.org/neutron/neutron-stable-stein.tar.gz
+      - neutron
       - http://tarballs.openstack.org/glance/glance-stable-stein.tar.gz
       - http://tarballs.openstack.org/cinder/cinder-stable-stein.tar.gz
       - horizon
@@ -514,21 +514,6 @@ parts:
     stage: [$etc]
     prime: [$etc]
 
-  neutron-config:
-    after: [openstack-projects]
-    plugin: dump
-    source: http://tarballs.openstack.org/neutron/neutron-stable-stein.tar.gz
-    organize:
-      etc/*.conf: etc/neutron/
-      etc/*.ini: etc/neutron/
-      etc/*.json: etc/neutron/
-      etc/rootwrap.d/*: etc/neutron/rootwrap.d/
-    filesets:
-      etc:
-        - etc/neutron/*
-    stage: [$etc]
-    prime: [$etc]
-
   glance-config:
     after: [openstack-projects]
     plugin: dump
@@ -943,7 +928,7 @@ parts:
     requirements:
       - requirements.txt
     constraints:
-      - ${SNAPCRAFT_STAGE}/patches/upper-constraints.txt
+      - https://raw.githubusercontent.com/openstack/requirements/stable/stein/upper-constraints.txt
     source: tools/cluster
     override-build: |
       # Hack to avoid conflict between openstack-projects'