Refactor clics spec implementation

[vmcj]

As mentioned in https://github.com/DOMjudge/domjudge/pull/1668, we should rewrite to use the same constant for the spec version.

In the future we might even want to read/detect the exact version and store it in a variable with the same constants https://github.com/DOMjudge/domjudge/pull/1668/files#diff-efa9e2dd8b5fccf408219fb062d6e943b7c49fa715163a4a600fbb23c941bae1R51 ...(?)

Originally posted by @eldering in https://github.com/DOMjudge/domjudge/pull/1668#discussion_r962571586