updates and corrections

• Add DOCKER_IMAGE_DBOCEANO variable in .env set as:
  • reeftemps/perl_dboceano by default on PROD
  • reeftemps/perl_dboceano:test on TEST
  • reeftemps/perl_dboceano:dev on DEV
• Use one Airflow variable with dev emails for all dags and one Airflow variable with user emails for each dag
• Set date_fin in export_operation table when export succeed in export_file dag
• Fix issue with export_file not triggered by load_file
• Modifs in body mail for load_file