Support Traefik v3

Summary

As reported in #5244 (comment 1888518210):

Hey, traefik 3 was launched yesterday (2024-04-29). As a result, the API traefik.containo.us/v1alpha1 is no longer supported and traefik.io/v1alpha1 must now be used. This is a quick fix but gitlab currently still creates a wrong IngressRouteTCP definition.

Perhaps this should be adjusted so that nobody runs into problems here in the future 😄

References

• https://github.com/traefik/traefik/releases/tag/v3.0.0
• https://docs.gitlab.com/charts/charts/traefik/
• Chart dependency in ./requirements.yaml
• ./examples/values-traefik-ingress.yaml
• charts/gitlab-shell/templates/traefik-tcp-ingressroute.yaml

Acceptance criteria

• GitLab Helm Charts support using Traefik v3