feat(FN-3986): remove PR lint pre-build and bun setup from pr-checks workfl

Removes the PR lint pre-build step from the GitHub Actions workflow and adds a new test suite (`ci-workflow.test.ts`) covering CI workflow behavior, with a small documentation update.

Fusion-Task-Id: FN-3986

.github/workflows/pr-checks.yml

@@ -29,12 +29,6 @@ jobs:
       - name: Install dependencies
         run: pnpm install --frozen-lockfile
 
-      - name: Install Bun
-        uses: oven-sh/setup-bun@v2
-
-      - name: Build plugins and core packages
-        run: pnpm build
-
       - name: Lint
         run: pnpm lint