feat: mlflow-fargate - add efs removal policy

[kukushking]

Describe your changes

Issue ticket number and link

• [FEATURE] configure EFS removal policy for mlflow-fargate module #8

Checklist before requesting a review

• I updated CHANGELOG.MD with a description of my changes
• If the change was to a module, I ran the code validation script (scripts/validate.sh)
• If the change was to a module, I have added thorough tests
• If the change was to a module, I have added/updated the module's README.md
• If a module was added, I added a reference to the module to the repository's README.md
• I verified that my code deploys successfully using seedfarmer apply

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.