Docker image updates for integration tests. (#26054)

* Sort packages to install.
* Add python-argparse to centos6 docker image.
* Add gcc and python dev lib to docker images.
* Add python cryptography to docker images.
* Add coverage using pip instead of OS packages.
* Update old pip versions in docker images.
* Exclude */pyshared/* from coverage reporting.

test/utils/docker/opensuse42.1/Dockerfile

@@ -20,7 +20,6 @@ RUN zypper --non-interactive --gpg-auto-import-keys refresh && \
     mercurial \
     openssh \
     postgresql-server \
-    python-coverage \
     python-cryptography \
     python-devel \
     python-httplib2 \
@@ -72,6 +71,6 @@ RUN ssh-keygen -q -t rsa1 -N '' -f /etc/ssh/ssh_host_key && \
     for key in /etc/ssh/ssh_host_*_key.pub; do echo "localhost $(cat ${key})" >> /root/.ssh/known_hosts; done
 # explicitly enable the service, opensuse default to disabled services
 RUN systemctl enable sshd.service
-RUN pip install junit-xml
+RUN pip install coverage junit-xml
 ENV container=docker
 CMD ["/sbin/init"]