Ansible: Drop usage of apt_key Ansible module

[NMertsch]

Our deployment playbook uses the Ansible module apt_key. From its docs:

Notes:

• The apt-key command used by this module has been deprecated. See the Debian wiki for details. This module is kept for backwards compatibility for systems that still use apt-key as the main way to manage apt repository keys.
• [...]

See also:

• ansible.builtin.deb822_repository: Add and remove deb822 formatted repositories.

Let's use the module deb822_repository instead. This blog post and the linked examples might be useful.