message: Update galera to alpine:latest and fix mariadb config
diff: ARG IMAGE_REPO
  FROM ${IMAGE_REPO:-lagoon}/commons as commons
  -FROM alpine:3.7
  +FROM alpine:latest
  MAINTAINER amazee.io
  @@ -93,7 +93,8 @@ RUN apk add --no-cache --virtual .common-run-deps \
  cd /tmp/maxscale-build && make && make install && \
  apk del --purge .common-build-deps && \
  rm -rf /tmp/* && \
  - rm -rf /var/cache/apk/*
  + rm -rf /var/cache/apk/* && \
  + rm -rf /etc/my.cnf*
  COPY entrypoints/ /lagoon/entrypoints/
  COPY maxscale.sql /docker-entrypoint-initdb.d/maxscale.sql
  