Non-deterministic result when merging an empty KllFloatsSketch with two others

Merging an empty KllFloatsSketch with two KllFloatsSketch, with 1 and 200 "items" respectively, does not always produce the same result

I would have expected the following test scenario to pass:

```
@Test
public void test() throws NoSuchAlgorithmException {

KllFloatsSketch t1 = KllFloatsSketch.newHeapInstance();
t1.update(1f);
byte[] tb1 = t1.toByteArray();

KllFloatsSketch t2 = KllFloatsSketch.newHeapInstance();
for(int i=0; i<200; i++) {
t2.update(1f*i);
}
byte[] tb2 = t2.toByteArray();

HashSet digests = new HashSet<>();
for(int i=0; i<30; i++) {
KllFloatsSketch start = KllFloatsSketch.newHeapInstance();

byte[] h1 = Arrays.copyOf(tb1, tb1.length);
byte[] h2 = Arrays.copyOf(tb2, tb2.length);

KllFloatsSketch kll1 = KllFloatsSketch.heapify(MemorySegment.ofArray(h1));
start.merge(kll1);

KllFloatsSketch kll2 = KllFloatsSketch.heapify(MemorySegment.ofArray(h2));
start.merge(kll2);

MessageDigest md5 = MessageDigest.getInstance("MD5");

BigInteger digest = new BigInteger(md5.digest(start.toByteArray()));
digests.add(digest);
System.out.println(digest);
}
assertEquals(1, digests.size());
}
```

The digests are:
```
115710133967357289505160160937439690295
-100233422360292323003164315945381734567
-100233422360292323003164315945381734567
-100233422360292323003164315945381734567
115710133967357289505160160937439690295
115710133967357289505160160937439690295
...
```

And therefore the test throws:
```
java.lang.AssertionError:
Expected :2
Actual :1
```

まず、KllFloatsSketch.newHeapInstance()、heapify()、merge()、toByteArray() に関する提供されたテストを再現します。1 個および 200 個のアイテムを含むスケッチをマージしたときの、繰り返しシリアライズされた結果を比較し、その後、マージとシリアライズの動作を追跡します。繰り返し実行したテストが 1 つの決定論的なダイジェストを生成し、常に成功すれば完了です。

索引モデルが issue の本文から書いたものです。