Simplified secret and variable definition

[asoltesz]

Currently, the parametrization are in these files:

• some secrets re in an Ansible vault in ansible/group_vars/all/vault.yml
• non-secret Ansible parameters are in ansible/group_vars/all/vars.yml
• secret and non-secret parameters are in ~/.solakube/${cluster}/variables.sh
• some parametrization is in terraform.tfvars

This is excessive and needs to be simplified.

Either remove the Ansible vault functionality and use only variables.sh or use an other unified solution for cleanly defining all parameters ans secrets in a single file.

Document the whole configuration process, so the original article is not needed anymore.