Draft: tf: Rename 'master' to 'controller'

Version Control Information

Source branch: bruno.sc/rename-master-to-controller
Target branch: devel

Commits:

* tf: Rename 'master' to 'controller'

This change only affects the Terraform layer (config+module) and is
transparent to the Terraform state and all layers above, e.g. Ansible.

Breaking: true

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Description

Related-to: !1317 (comment 1968457687)
After: !1317 (merged), !1265 (merged)
Closes: #674

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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 in RST format added in latest commit