Bump distribution_ci_tools to Debian 13

Debian 12 ships with git v2.39.5, which does not support the proactive auth setting. We need git v2.46.0. Debian 13 ships with git v2.47.3.

Changes

• Bump the distribution_ci_tools image base from Debian 12 to Debian 13 (trixie).
• Drop software-properties-common, which was removed in Debian 13.
• Fix the gcloud / gke-gcloud-auth-plugin install, which broke as a result of the above:
  • Removing software-properties-common also removed apt-key. Replace apt-key add - with gpg --batch --yes --dearmor writing to /usr/share/keyrings/cloud.google.gpg, referenced via signed-by= in the apt source. The --batch --yes flags keep gpg from trying to open /dev/tty during the non-interactive build.
  • Debian 13 ships Python 3.13, which removed the deprecated imp module. The pinned gcloud 434.0.0 still imports imp and fails with ModuleNotFoundError: No module named 'imp', so bump GCLOUD_VERSION and GCLOUD_GKE_AUTH_PLUGIN_VERSION to 571.0.0.
  • The gke auth plugin apt package was renamed from google-cloud-sdk-gke-gcloud-auth-plugin to google-cloud-cli-gke-gcloud-auth-plugin (the old name no longer carries recent versions). Install the new name, and drop the redundant repository/signing-key setup from the snippet since the gcloud snippet already configures it beforehand (this also clears apt's "configured multiple times" warning).

Relates to https://gitlab.com/gitlab-org/gitlab/-/work_items/591939