Draft: [TEST] Adding 15.9.3, 15.8.5, 15.7.9 blog post - DO NOT MERGE
Add blog post for 15.9.3, 15.8.5, 15.7.9 patch release.
Patch issue: gitlab-org/release/tasks#5189 (closed)
Related to gitlab-com/gl-infra/delivery#2839 (closed)
Edited by Mayra Cabrera