rejigged mysql install procedure

Former-commit-id: 5c612eb7

roles/mysql/vars/Ubuntu_18.yml

 server_packages:
-#  - python
-#  - python-dev
-#  - libmysqlclient-dev
-#  - python-pip
-#  - libapache2-mod-wsgi
-#  - python-mysql.connector
-#  - mysql-server
-#  - python-mysqldb
+ - python
+ - python-dev
+ - libmysqlclient-dev
+ - python-pip
+ - libapache2-mod-wsgi
+ - python-mysql.connector
+ - mysql-server
+ - python-mysqldb
  - mariadb-server
 
 client_packages:
-  - python
-  - mariadb-client
+ - python
+ - mariadb-client
 
-sqlServiceName: "mariadb-server"
+sqlServiceName: "mariadb"