feature(key_vault): remove caf provider reference

[filipefigueredo]

Description

The main goal of this PR is to remove the unused CAF provider reference from the key_vault module

PR Checklist

Please ensure the following before submitting this PR:

• [X] You complied with the code style of this project.
• [X] You formatted all Terraform configuration files to a canonical format (Hint: terraform fmt).
• [X] You validated all Terraform configuration files (Hint: terraform validate).
• [X] You executed a speculative plan, showing what actions Terraform would take to apply the current configuration (Hint: terraform plan).
• [ ] The documentation was updated (README.md, CHANGELOG.md, etc.).
• [ ] Whenever possible, the dependencies were updated to the latest compatible versions.

PR Type

What kind of change does this PR introduce?

• [ ] Bugfix.
• [X] Feature
• [ ] Code style update (formatting, local variables)
• [ ] Refactoring (no functional changes, no interface changes)
• [ ] Build related changes
• [X] CI related changes
• [ ] Documentation content changes.
• [ ] Other... Please describe:

What is the new behavior?

N/A

How to test it

N/A

Does this PR introduce a breaking change?

• [ ] Yes.
• [X] No.

Other information

[github-actions[bot]]

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