Avoid database corruption on docker stop or docker compose stop

[handfreezer]

Changes in init.sh (entrypoint) of container to manage a clean stop of database on docker stop or docker compose stop

Bug

Have a look here from MariaDB JIRA: https://jira.mariadb.org/browse/MDEV-34047
=> [your container entrypoint is intentionally corrupting your database after any service start failure with "rm /var/lib/mysql/ib_logfile*" [ref]. It won't be recoverable]

Description

init.sh script will trap the SIGTERM signal sent by docker on stop, and then request a "service_mariadb stop" before touching a file to stop the main process (PID=1)

Types of changes

• Bug fix (non-breaking change which fixes)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
  • This change is only breaking for integrators, not for external standards or end-users.
• Documentation improvement

PR checklist

• I have checked there is no other PR open for the same change.
• I have read the [La ligne directrice pour contribuer à ce projet / Contribution guidelines for this project).
• I grant the project the right to include and distribute the code under the GNU.
• I have added tests to cover my changes.
• I have verified that the code complies with the projects coding standards.
• [Required for new sniffs] I have added MD documentation for the sniff.