Update test name

Author: JoshRosen

core/src/test/java/org/apache/spark/util/collection/unsafe/sort/UnsafeInMemorySorterSuite.java

@@ -56,11 +56,8 @@ public void testSortingEmptyInput() {
     assert(!iter.hasNext());
   }
 
-  /**
-   * Tests the type of sorting that's used in the non-combiner path of sort-based shuffle.
-   */
   @Test
-  public void testSortingOnlyByPartitionId() throws Exception {
+  public void testSortingOnlyByIntegerPrefix() throws Exception {
     final String[] dataToSort = new String[] {
       "Boba",
       "Pearls",