CI: Don't run PANDAS_DATA_MANAGER=array test for downstream tests (#46253)

Author: mroeschke

ci/run_tests.sh

@@ -33,9 +33,10 @@ fi
 echo $PYTEST_CMD
 sh -c "$PYTEST_CMD"
 
-if [[ "$PANDAS_DATA_MANAGER" != "array" ]]; then
+if [[ "$PANDAS_DATA_MANAGER" != "array" && "$PYTEST_TARGET" == "pandas" ]]; then
     # The ArrayManager tests should have already been run by PYTEST_CMD if PANDAS_DATA_MANAGER was already set to array
-    PYTEST_AM_CMD="PANDAS_DATA_MANAGER=array pytest -n $PYTEST_WORKERS  --dist=loadfile $TEST_ARGS $COVERAGE pandas"
+    # If we're targeting specific files, e.g. test_downstream.py, don't run.
+    PYTEST_AM_CMD="PANDAS_DATA_MANAGER=array pytest -n $PYTEST_WORKERS --dist=loadfile $TEST_ARGS $COVERAGE pandas"
 
     if [[ "$PATTERN" ]]; then
       PYTEST_AM_CMD="$PYTEST_AM_CMD -m \"$PATTERN and arraymanager\""