message: variables renamed, and update image to mariadb.
diff: ARG IMAGE_REPO
  -FROM ${IMAGE_REPO:-lagoon}/centos7-mariadb10
  +FROM ${IMAGE_REPO:-lagoon}/mariadb
  -ENV MYSQL_DATABASE=infrastructure \
  - MYSQL_USER=api \
  - MYSQL_PASSWORD=api
  +ENV MARIADB_DATABASE=infrastructure \
  + MARIADB_USER=api \
  + MARIADB_PASSWORD=api
  COPY ./docker-entrypoint-initdb.d /docker-entrypoint-initdb.d/
  COPY ./rerun_initdb.sh /rerun_initdb.sh
  