Fix dbcounter install on Debian Bullseye

The dbcounter install on Debian Bullseye is broken in a really fun way.
The problem is that we end up mixing pypi openssl and distro
cryptography under pip and those two versions of libraries are not
compatible.

The reason this happens is that debian's pip package debundles the pip
deps. This splits them out into /usr/share/python-wheels and it will
prefer distro versions of libraries over pypi installed versions of
libraries. But if a pypi version is installed and a distro version is
not then the pypi version is used. If the pypi version of library A does
not work with distro version of library B then debundled pip breaks.
This has happened with crypytography and pyOpenSSL.

This happens because urllib3 (a debundled pip dep) appears to use
pyopenssl conditionally. Novnc depends on python3-cryptography, and
openstack depends on cryptogrpahy from pypi ensuring we get both a
distro and a pypi version installed. However, pyOpenSSL is only pulled
in from pypi via openstack deps. This leaves debundled urllib3
attempting to use pypi pyOpenSSL with distro cryptography and that combo
isn't valid due to an interface change.

To fix this we install python3-openssl ensuring that debundled pip will
use distro pyOpenSSL with distro cryptography making everything happy
again. But we only do this when we install novnc as novnc is what pulls
in distro cryptography in the first place. We can't simply install
python3-openssl on all debuntu platforms because this breaks Ubuntu
Focal in the other direction. On Ubuntu focal distro pip uses distro
pyOpenSSL when no pypi pyOpenSSl is installed (prior to keystone
install) and is not compatible with pypi cryptography.

Honestly, this whole intersection between distro and pypi installs of
cryptography and pyOpenSSL could probably be made cleaner. One option
would be for us to always install the constraints version of both
packages from pypi and the distro pacakges very early in the devstack
run. But that seems far more complicated so I'm not attempting that
here.

Change-Id: I0fc6a8e66e365ac49c6c7ceb4c71c68714b9f541

lib/nova

@@ -885,8 +885,23 @@ function install_nova {
         # a websockets/html5 or flash powered VNC console for vm instances
         NOVNC_FROM_PACKAGE=$(trueorfalse False NOVNC_FROM_PACKAGE)
         if [ "$NOVNC_FROM_PACKAGE" = "True" ]; then
+            # Installing novnc on Debian bullseye breaks the global pip
+            # install. This happens because novnc pulls in distro cryptography
+            # which will be prefered by distro pip, but if anything has
+            # installed pyOpenSSL from pypi (keystone) that is not compatible
+            # with distro cryptography. Fix this by installing
+            # python3-openssl (pyOpenSSL) from the distro which pip will prefer
+            # on Debian. Ubuntu has inverse problems so we only do this for
+            # Debian.
+            local novnc_packages
+            novnc_packages="novnc"
+            GetOSVersion
+            if [[ "$os_VENDOR" = "Debian" ]] ; then
+                novnc_packages="$novnc_packages python3-openssl"
+            fi
+
             NOVNC_WEB_DIR=/usr/share/novnc
-            install_package novnc
+            install_package $novnc_packages
         else
             NOVNC_WEB_DIR=$DEST/novnc
             git_clone $NOVNC_REPO $NOVNC_WEB_DIR $NOVNC_BRANCH