Scope the pre-Rspec wait barrier to Rspec's actual dependencies #patch

[wesrich]

Why

The wait-all: true immediately before Run Rspec Tests in rails-ci.yml blocks on every background step launched so far in the job — including Rubocop, ESLint, Brakeman, Dependency Audit, and Project Stats. None of those publish anything Rspec reads: they report their own check results independently later in the job (Brakeman via reviewdog, Rubocop via GitHub-format output, Project Stats via a later Publish Project Stats Check step).

Measured across two real bgea_volunteer_care CI runs, every dependency Rspec actually needs (gems/Ruby, apt packages, yarn/node_modules, compiled assets, the Playwright browser, parallel test DBs) was ready well before the old barrier released, but Brakeman (and once, Rubocop's slim_lint step) was consistently the last background step to finish — and Rspec started within ~2ms of it finishing every time. That's ~11s of pure idle time on a 32vcpu run and ~22s on an 8vcpu run, wasted purely on steps Rspec doesn't need. This compounds across every CI run of every app using this shared workflow.

What Changed

• Added id:s to Compile Assets, Install Playwright Chromium Browser, and Setup Parallel Databases so they can be referenced explicitly
• Replaced the wait-all: true before Run Rspec Tests with a wait: scoped to just Rspec's real dependencies: install-ruby, install-apt, install-yarn, compile-assets, install-playwright, setup-parallel-databases
• Rubocop/ESLint/Brakeman/Dependency Audit/Project Stats now run concurrently with Rspec instead of gating it
• Replaced the later wait: [save-asset-cache] (right after Run Rspec Tests) with wait-all: true, so those background lint/security/stats steps are still joined before the job's final parallel block — preserving the guarantee that a lint/security failure fails the job and that steps.project-stats.outputs.table is populated before it's published

Test plan

• Merge and tag a new v3.x.y release
• Confirm a consuming app's CI run (e.g. bgea_volunteer_care) still fails correctly when Rubocop/Brakeman/Dependency Audit is broken
• Confirm Run Rspec Tests now starts as soon as its real dependencies are ready, not gated on Brakeman/Rubocop

Screenshots

N/A — no UI changes