Remove .ci directory

[tobiasdiez]

Removes the .ci folder. It contains mostly outdated scripts that were used for gitlab CI.

• A few scripts are needed for building the docker image, they are moved to docker
• A few other scripts are used in the current github ci, they are moved to .github/workflows

📝 Checklist

• The title is concise and informative.
• The description explains in detail what this PR is about.
• I have linked a relevant issue or discussion.
• I have created tests covering the changes.
• I have updated the documentation and checked the documentation preview.

⌛ Dependencies

[github-actions]

Documentation preview for this PR (built with commit 8441838; changes) is ready! 🎉
This preview will update shortly after each push to this PR.

[user202729]

Looks good to me. Though the permission change on sage-version.sh looks accidental.

Also not sure where docker-exec-script should belong (if it isn't used to build docker I assume putting there is fine? Might be worth creating a docker/README.md then)

@saraedum Are the removed scripts useless now?

[tobiasdiez]

Also not sure where docker-exec-script should belong (if it isn't used to build docker I assume putting there is fine? Might be worth creating a docker/README.md then)

It's only used in the github ci that is based on docker. Not for building the docker image that we provide. Thus it is similar to write-dockerfile.