GH-1455: Keep TestReservationListener from closing a pool still in use

testErrorThrownFromReservationListener closed its listenable
NativeMemoryPool right after the scan failed. Arrow C++ can still be
running the failed scan's work on its thread pools, and that work keeps
using the pool, so freeing it could crash the test JVM. Leave the pool
open in that test, and close the scanner and dataset in
collectResultFromFactory when the scan fails.

Author: jbonofre

dataset/src/test/java/org/apache/arrow/dataset/TestDataset.java

@@ -68,12 +68,9 @@ protected BufferAllocator rootAllocator() {
 
   protected List<ArrowRecordBatch> collectResultFromFactory(
       DatasetFactory factory, ScanOptions options) {
-    final Dataset dataset = factory.finish();
-    final Scanner scanner = dataset.newScan(options);
-    try {
-      final List<ArrowRecordBatch> ret = collectTaskData(scanner);
-      AutoCloseables.close(scanner, dataset);
-      return ret;
+    try (Dataset dataset = factory.finish();
+        Scanner scanner = dataset.newScan(options)) {
+      return collectTaskData(scanner);
     } catch (RuntimeException e) {
       throw e;
     } catch (Exception e) {

dataset/src/test/java/org/apache/arrow/dataset/jni/TestReservationListener.java

@@ -122,9 +122,9 @@ public void unreserve(long size) {
         },
         errorMessage);
     long reservation = reserved.get();
-    AutoCloseables.close(pool);
-    long finalReservation = reserved.get();
     assertEquals(initReservation, reservation);
-    assertEquals(initReservation, finalReservation);
+    // The failed scan can leave work running on Arrow C++ threads that still uses the pool,
+    // and closing the scanner doesn't wait for it. Closing the pool here would free it under
+    // that work and crash the JVM, so the pool is left open (GH-1455).
   }
 }