jenkins: run all car tests with one command (#30661)

* run all jenkins car tests in one script, less down time?

* fix

* speed up

* u

Jenkinsfile

@@ -234,9 +234,8 @@ node {
       'car tests': {
         pcStage("car tests") {
           sh label: "build", script: "selfdrive/manager/build.py"
-          sh label: "test_models.py", script: "INTERNAL_SEG_CNT=250 INTERNAL_SEG_LIST=selfdrive/car/tests/test_models_segs.txt FILEREADER_CACHE=1 \
-              pytest selfdrive/car/tests/test_models.py"
-          sh label: "test_car_interfaces.py", script: "MAX_EXAMPLES=100 pytest selfdrive/car/tests/test_car_interfaces.py"
+          sh label: "run car tests", script: "cd selfdrive/car/tests && MAX_EXAMPLES=100 INTERNAL_SEG_CNT=250 FILEREADER_CACHE=1 \
+              INTERNAL_SEG_LIST=selfdrive/car/tests/test_models_segs.txt pytest test_models.py test_car_interfaces.py"
         }
       },