Remove MariaDB-shared in openstack-base

After we switched to PyMySQL in openstack-base, there is no need to
compile MySQL-python thus to install MariaDB-shared package as
a workaround for busted percona packages.

TrivialFix
Related-Bug: #1526129

Change-Id: I93b4bee9d42427b493dac3a0039e0b1a9cac9f71

docker/openstack-base/Dockerfile.j2

@@ -2,12 +2,10 @@ FROM {{ namespace }}/{{ image_prefix }}base:{{ tag }}
 MAINTAINER {{ maintainer }}
 
 {% if base_distro in ['fedora', 'centos', 'oraclelinux', 'rhel'] %}
-# TODO(mandre) remove MariaDB-shared once Percona has fixed its packaging issue
 RUN yum -y install \
         git \
         iproute \
         mariadb-libs \
-        MariaDB-shared \
         openssl \
     && yum clean all