feat: get secrets from vault

Feature

Summary

This MR provides a basic integration of Vault, a central secret store. Mainly it moves away from GitLab Secret Variables and takes these information from Vault. This requires changes in the CI scripts only.

Compliance to “Definition of Done”

• Unit tests passed
• Code reviewed
• Product Owner accepts the User Story

Documentation

• I updated the README (if applicable)
• I provided my functions with appropriate documentation
• I updated existing documentation

Tests

Are we able to test this new feature?

• Yes, everything can be done via unit tests.
• Yes, you can test by following these steps: …
• No, it is not possible.

Changelog

• I added a statement to the CHANGELOG.

Version number

• I bumped the version number in build.properties.

Closes

Closes 21091 (projects)

Logs and Screenshots