Add `kind/internal` label to `internal` issue label in default config

[hielfx]

Motivation

Currently, we are using the kind/internal label, but we have not included it in the default labels: https://github.com/InditexTech/gh-sherpa/blob/main/internal/config/default-config.yml#L58

Acceptance criteria

• [ ] internal -> kind/internal map is configured in the default config file.