Allow partial tests to take 20 minutes, use all cores (#74079)

.github/workflows/ci.yaml

@@ -803,7 +803,7 @@ jobs:
             tests
       - name: Run pytest (partially)
         if: needs.changes.outputs.test_full_suite == 'false'
-        timeout-minutes: 10
+        timeout-minutes: 20
         shell: bash
         run: |
           . venv/bin/activate
@@ -818,7 +818,7 @@ jobs:
             -qq \
             --timeout=9 \
             --durations=10 \
-            -n 0 \
+            -n auto \
             --cov="homeassistant.components.${{ matrix.group }}" \
             --cov-report=xml \
             --cov-report=term-missing \