Revert "Fix consistently failing CentOS gate"

This reverts commit 17e0de6aa6.

This change should have never merged. There is something else going on
here and the bug doesnt fully invetigate the issue. Using a mix of
system and pip packages is not acceptable and can cause problems.
In this case the packaged mysql has a KNOWN issue that we fixed in
liberty by switching to the pip installed package.

Change-Id: Ie10116010156c13742a0a5d37c440c713e4698e5

docker/kolla-toolbox/Dockerfile.j2

@@ -10,7 +10,6 @@ RUN yum -y install \
         libxml2-devel \
         libxslt-devel \
         MariaDB-devel \
-        MySQL-python \
         openssl-devel \
         python-devel \
         openssh-clients \
@@ -27,7 +26,6 @@ RUN apt-get -y --no-install-recommends install \
         libmariadbclient-dev \
         libssl-dev \
         libxslt1-dev \
-        python-mysqldb \
         python-dev \
     && apt-get clean
 
@@ -37,6 +35,7 @@ RUN curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py \
     && python get-pip.py \
     && rm get-pip.py \
     && pip --no-cache-dir install \
+        MySQL-python \
         os-client-config==1.16.0 \
         pyudev \
         shade==1.4.0