stx-openstackclients: Move all clients to DIST

In [1], two OpenStack clients were moved to the `DIST_PACKAGES` section
of the `stx-openstackclients` container image build recipe due to the
need to use packages patched exclusively for StarlingX:

  * python3-cinderclient;
  * python3-openstackclient.

Although this change served its purpose, it had a side-effect that
caused the main CLI, `openstack`, to stop recognizing other clients
installed via `PIP_PACKAGES`.

This occurred because once installed via `DIST_PACKAGES`, both
`cinderclient` and `openstackclient` started to reside in the
dist-packages/ directory, while all other clients continued to reside in
site-packages/. As `openstackclient` is the one responsible for the main
CLI, it stopped finding the other clients because its search directory
changed to dist-packages/.

Therefore, in this change, we chose to move all OpenStack clients to
DIST_PACKAGES. This way, it is guaranteed that the main CLI will
correctly identify the other OpenStack clients.

[1] https://review.opendev.org/c/starlingx/openstack-armada-app/+/896129

Test Plan:
PASS - Build stx-debian base image
PASS - Build stx-openstackclients container image
PASS - Upload/apply stx-openstack
PASS - Upload built image to the system's local registry and perform
       a helm-override to use it in the OpenStack clients container
PASS - Run commands that had disappeared since the merge of [1], e.g.,
       the ones provided by `heatclient`:
       * openstack stack list
       * openstack stack create
       ...
PASS - Remove/delete stx-openstack

Closes-Bug: 2039096

Co-authored-by: Lucas de Ataides <lucas.deataidesbarreto@windriver.com>
Co-authored-by: Romulo Leite <romulo.leite@windriver.com>
Change-Id: I61d653ceef07f99568a21b4ad6f6dceffed22ca1
Signed-off-by: Luan Nunes Utimura <LuanNunes.Utimura@windriver.com>

upstream/openstack/python-openstackclient/debian/stx-openstackclient.stable_docker_image

@@ -4,25 +4,25 @@ PROJECT=infra
 PROJECT_REPO=nil
 DIST_REPOS="OS +openstack"
 PIP_PACKAGES="
-  aodhclient \
   httplib2 \
   ndg-httpsclient \
   pyasn1 \
   pycryptodomex \
-  pyopenssl \
-  python-barbicanclient \
-  python-glanceclient \
-  python-heatclient \
-  python-keystoneclient \
-  python-neutronclient \
-  python-novaclient \
-  python-swiftclient \
+  pyopenssl
 "
 DIST_PACKAGES="
   bash-completion \
   libffi-dev \
   openssl \
   python-dev \
+  python3-aodhclient \
+  python3-barbicanclient \
   python3-cinderclient \
+  python3-glanceclient \
+  python3-heatclient \
+  python3-keystoneclient \
+  python3-neutronclient \
+  python3-novaclient \
   python3-openstackclient \
+  python3-swiftclient
 "