ci: fold failpoints test into Test Workspace job

The standalone test_failpoints_feature job took 21min on first run
(cold cache; the omnigraph-engine crate has lance + datafusion deps
that make any fresh build expensive). Folding into Test Workspace
shares the warm cache so the failpoints invocation is incremental —
~30s vs 21min on subsequent runs, and within the workspace job's
existing budget.

The failpoints feature is gated behind a Cargo flag and only adds
the small `fail` crate dep + a few feature-gated code paths; it
doesn't change the dep tree of any other crate.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.github/workflows/ci.yml

@@ -161,6 +161,16 @@ jobs:
           OMNIGRAPH_UPDATE_OPENAPI: ${{ (github.event_name == 'pull_request' && github.event.pull_request.head.repo.full_name == github.repository) && '1' || '' }}
         run: cargo test --workspace --locked
 
+      - name: Run failpoints feature test
+        if: needs.classify_changes.outputs.run_full_ci == 'true'
+        # Run after the workspace test so the build cache is warm —
+        # enabling --features failpoints is just an incremental rebuild
+        # of omnigraph-engine + the small `fail` crate, not the full
+        # dep tree (lance, datafusion). A separate job with its own
+        # cache key would be a fresh ~20min build on first run; this
+        # is ~30s on a warm cache.
+        run: cargo test --locked -p omnigraph-engine --features failpoints --test failpoints
+
       - name: Commit regenerated openapi.json to PR branch
         if: |
           needs.classify_changes.outputs.run_full_ci == 'true' &&
@@ -239,48 +249,6 @@ jobs:
         if: needs.classify_changes.outputs.run_full_ci == 'true'
         run: cargo test --locked -p omnigraph-server --features aws
 
-  test_failpoints_feature:
-    name: Test omnigraph-engine --features failpoints
-    needs: classify_changes
-    runs-on: ubuntu-latest
-    timeout-minutes: 30
-    permissions:
-      contents: read
-    env:
-      CARGO_TERM_COLOR: always
-    steps:
-      - name: Skip for text-only changes
-        if: needs.classify_changes.outputs.run_full_ci != 'true'
-        run: echo "Text-only change detected; skipping failpoints feature build."
-
-      - name: Checkout source
-        if: needs.classify_changes.outputs.run_full_ci == 'true'
-        uses: actions/checkout@v5.0.1
-
-      - name: Install system dependencies
-        if: needs.classify_changes.outputs.run_full_ci == 'true'
-        run: |
-          sudo apt-get update
-          sudo apt-get install -y protobuf-compiler libprotobuf-dev
-
-      - name: Install Rust stable
-        if: needs.classify_changes.outputs.run_full_ci == 'true'
-        uses: dtolnay/rust-toolchain@stable
-        with:
-          toolchain: stable
-
-      - name: Cache Rust build data
-        if: needs.classify_changes.outputs.run_full_ci == 'true'
-        uses: Swatinem/rust-cache@v2
-        with:
-          workspaces: |
-            . -> target
-          key: failpoints-feature
-
-      - name: Run failpoints test suite
-        if: needs.classify_changes.outputs.run_full_ci == 'true'
-        run: cargo test --locked -p omnigraph-engine --features failpoints --test failpoints
-
   rustfs_integration:
     name: RustFS S3 Integration
     needs: