chore: Removing pg_dead_tup_rate_tuples

Relates to comment from gitlab-com/gl-infra/scalability#2582 (comment 1693463995). groupdatabase is not using the recording rule gitlab_component_utilization:pg_dead_tup_rate_tuples:1h.

As we don't use the it, we can get rid of it. Worst case we get it back with a git revert.