Install os-net-config as a package, not an element

This change drops use of the os-net-config element from
t-h-t and simply installs the tool as a standard package.

The use of os-net-config has been deprecated in favor of
the new template styles for awhile now. The new hook gives better
signals when errors occur configuring the physical networks.

Change-Id: Ie4f5d771a16ea453b470be8ea103b2bde4aa892a
Related-bug: #1695091

image-yaml/overcloud-hardened-images.yaml

@@ -10,7 +10,6 @@ disk_images:
       - overcloud-compute
       - overcloud-ceph-storage
       - puppet-modules
-      - os-net-config
       - stable-interface-names
       - bootloader
       - element-manifest
@@ -36,6 +35,7 @@ disk_images:
       - python-heat-agent-docker-cmd
       - python-heat-agent-json-file
       - screen
+      - os-net-config
     options:
       - "--min-tmpfs 5"
     environment:

image-yaml/overcloud-images.yaml

@@ -11,7 +11,6 @@ disk_images:
       - overcloud-compute
       - overcloud-ceph-storage
       - puppet-modules
-      - os-net-config
       - stable-interface-names
       - grub2
       - element-manifest
@@ -29,6 +28,7 @@ disk_images:
       - ntp
       - device-mapper-multipath
       - openstack-heat-agents
+      - os-net-config
     options:
       - "--min-tmpfs 5"
     environment:

image-yaml/overcloud-odl-rhel7.yaml

@@ -10,7 +10,6 @@ disk_images:
            - dhcp-all-interfaces
            - os-collect-config
            - puppet-modules
-           - os-net-config
            - stable-interface-names
            - grub2-deprecated
          packages:
@@ -23,4 +22,5 @@ disk_images:
            - python-heat-agent-ansible
            - python-heat-agent-docker-cmd
            - python-heat-agent-json-file
+           - os-net-config
          options:

releasenotes/notes/os_net_config_packaging-36b94a08bbb3e11d.yaml

@@ -0,0 +1,17 @@
+---
+features:
+  - |
+    Install os-net-config as an RPM package directly via DIB rather than
+    rely on the os-net-config element. This change will allow us to
+    deprecated further use of tripleo-image-elements for this feature.
+upgrade:
+  - |
+    In the Ocata release we started using a tripleo-heat-templates script
+    to drive os-net-config. This approach gave us better signal handling
+    capabilities, reduces our dependencies on os-apply-config, and makes
+    it easier to integrate and fine tune network configuration with
+    for example custom mapping files. Users who have network scripts
+    using the older 'os-apply-config' format will need to update
+    to the new t-h-t script format as part of this change. All
+    in tree templates were updated in t-h-t as part of
+    git commit 2c11e9e179178d074af91d8c5c798078ac3e0966.