[SPARK-17405] RowBasedKeyValueBatch should use default page size to prevent OOMs

## What changes were proposed in this pull request?

Before this change, we would always allocate 64MB per aggregation task for the first-level hash map storage, even when running in low-memory situations such as local mode. This changes it to use the memory manager default page size, which is automatically reduced from 64MB in these situations.

cc ooq JoshRosen

## How was this patch tested?

Tested manually with `bin/spark-shell --master=local[32]` and verifying that `(1 to math.pow(10, 3).toInt).toDF("n").withColumn("m", 'n % 2).groupBy('m).agg(sum('n)).show` does not crash.

Author: Eric Liang <ekl@databricks.com>

Closes #15016 from ericl/sc-4483.

sql/catalyst/src/main/java/org/apache/spark/sql/catalyst/expressions/RowBasedKeyValueBatch.java

@@ -37,19 +37,18 @@ import org.slf4j.LoggerFactory;
  * We use `FixedLengthRowBasedKeyValueBatch` if all fields in the key and the value are fixed-length
  * data types. Otherwise we use `VariableLengthRowBasedKeyValueBatch`.
  *
- * RowBasedKeyValueBatch is backed by a single page / MemoryBlock (defaults to 64MB). If the page
- * is full, the aggregate logic should fallback to a second level, larger hash map. We intentionally
- * use the single-page design because it simplifies memory address encoding & decoding for each
- * key-value pair. Because the maximum capacity for RowBasedKeyValueBatch is only 2^16, it is
- * unlikely we need a second page anyway. Filling the page requires an average size for key value
- * pairs to be larger than 1024 bytes.
+ * RowBasedKeyValueBatch is backed by a single page / MemoryBlock (ranges from 1 to 64MB depending
+ * on the system configuration). If the page is full, the aggregate logic should fallback to a
+ * second level, larger hash map. We intentionally use the single-page design because it simplifies
+ * memory address encoding & decoding for each key-value pair. Because the maximum capacity for
+ * RowBasedKeyValueBatch is only 2^16, it is unlikely we need a second page anyway. Filling the
+ * page requires an average size for key value pairs to be larger than 1024 bytes.
  *
  */
 public abstract class RowBasedKeyValueBatch extends MemoryConsumer {
   protected final Logger logger = LoggerFactory.getLogger(RowBasedKeyValueBatch.class);
 
   private static final int DEFAULT_CAPACITY = 1 << 16;
-  private static final long DEFAULT_PAGE_SIZE = 64 * 1024 * 1024;
 
   protected final StructType keySchema;
   protected final StructType valueSchema;
@@ -105,7 +104,7 @@ public abstract class RowBasedKeyValueBatch extends MemoryConsumer {
     this.keyRow = new UnsafeRow(keySchema.length());
     this.valueRow = new UnsafeRow(valueSchema.length());
 
-    if (!acquirePage(DEFAULT_PAGE_SIZE)) {
+    if (!acquirePage(manager.pageSizeBytes())) {
       page = null;
       recordStartOffset = 0;
     } else {