Provide packages for SUSE Linux Enterprise Server SLES 15.6

SLES 15.6 was released on [June 26, 2024], but there are no GitLab-ee packages for it: the latest versions available at https://packages.gitlab.com/app/gitlab/gitlab-ee/ are for 15.2.

Similar to another ticket regarding OpenSUSE 15.6 #8752 (closed)

Acceptance Criteria

Steps

  1. Ensure Packagecloud supports it: https://packagecloud.io/docs#anchor-sles
  2. Create builder images at https://gitlab.com/gitlab-org/gitlab-omnibus-builder
  3. Add CI jobs to build and release the packages using the builder images
  4. Update supported OSes documentation
Edited by Clemens Beck