CI: use less parallel jobs for cars (#32458)

* CI: use less parallel jobs for cars

* 2

.github/workflows/selfdrive_tests.yaml

@@ -298,7 +298,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        job: [0, 1, 2, 3, 4]
+        job: [0, 1]
     steps:
     - uses: actions/checkout@v4
       with:
@@ -318,7 +318,7 @@ jobs:
         ${{ env.RUN }} "$PYTEST selfdrive/car/tests/test_models.py && \
                         chmod -R 777 /tmp/comma_download_cache"
       env:
-        NUM_JOBS: 5
+        NUM_JOBS: 2
         JOB_ID: ${{ matrix.job }}
     - name: "Upload coverage to Codecov"
       uses: codecov/codecov-action@v4