Add mariadb-client to prod image.

Add mariadb client to easier debugging of deployments.

docker/dockerfiles/full-no-locales

@@ -11,7 +11,7 @@ ENV PYTHONUNBUFFERED=1
 
 RUN apt-get update && \
     apt-get install -y --no-install-recommends \
-             libmariadbclient18 optipng \
+             libmariadbclient18 optipng mariadb-client \
              libxslt1.1 && \
     rm -rf /var/lib/apt/lists/*