Lint more/all YAML files in CI

Background

!85510 (merged) fixed a YAML syntax error which we didn't catch in !85426 (merged)

Proposal

Extend our YAML linting to the files in db/docs, or possibly all YAML files.

It looks like we can extend the .yaml-lint-patterns at https://gitlab.com/gitlab-org/gitlab/blob/7415bc1ed4b4a0d4ea0b6e110bb811ff1d0357e8/.gitlab/ci/rules.gitlab-ci.yml#L174-178, but then also have to pass the same paths to yamllint at https://gitlab.com/gitlab-org/gitlab/blob/7415bc1ed4b4a0d4ea0b6e110bb811ff1d0357e8/.gitlab/ci/yaml.gitlab-ci.yml#L10-13