fix(build): add UBI 9 compiler tool‑chain and split fast/slow tests (#1970)

* build_container.sh
  - append `python3.11‑devel gcc make` to UBI 9 dnf line so C‑ext wheels build.
* tests/integration
  - + test_ubi9_toolchain.py   (fast; asserts pkgs exist in Containerfile)
  - + test_ubi9_compiles.py    (slow; @integration, compiles hello‑world in built image)
  - – test_container_build.py  (removed heavyweight test)
* pytest.ini
  - register `integration` marker.
* CI
  - tests.yml ⇒ `pytest -m "not integration"`
  - providers_build.yml ⇒ run integration compiler smoke for container jobs

.github/workflows/tests.yml

@@ -35,6 +35,10 @@ jobs:
           pip install -r requirements.txt pytest
           pip install -e .
 
+      - name: Run fast unit & smoke tests
+        run: |
+          pytest -m "not integration"
+
       - name: Build providers
         run: |
           llama stack build --template ${{ matrix.provider }} --image-type venv