Resolve "Gitlab Terraform state breaks for other users"

Version Control Information

Source branch: 612-gitlab-terraform-state-breaks-for-other-users
Target branch: devel

Description

Actual state:

• Automatically delete local Terraform state files when migrating local -> http;
• Automatically delete Terraform state file from GitLab when migrating http -> local;
• Automatically delete Terraform state file from GitLab when destroying a cluster;
• Only allow to have all GitLab variables set OR all GitLab variables unset.

Closes: #612 (closed)

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Merge Prerequisites

• MR title (and description) are descriptive
• Code is readable and syntactically correct
• Code is understandable
• Documentation has been updated, if necessary
• Commit messages look good
• Release note file added in latest commit

As a developer: please do not tick these boxes yourself. As a reviewer: please get yourself a hot cold beverage.

Closes #612 (closed)