Removing tags from our small SaaS runner on Linux

This post announces a change in the tagging strategy for GitLab's small SaaS runner on Linux. It details the deprecation of existing tags (`docker`, `linux`) and the introduction of a new, consistent tag (`saas-linux-small-amd64`). It provides examples of affected and unaffected job configurations and instructs users on how to update their `.gitlab-ci.yaml` files to avoid job failures.