Knn query vector is serialized as array of double, not float

### Java API client version

9.0.3

### Java version

21

### Elasticsearch Version

9.0.3

### Problem description

KnnQuery models `queryVector` as `List` but serializes as `List`, adding roughly 9 bytes per value. For `dense_vector` of typical sizes, e.g. 1024, this can add roughly 9kb to the uncompressed request body.

This reason is due to the float being cast to a double as consumed by `jakarta.json.stream.JsonGenerator.write(double)` for which does not have a `write(float)` overload. The solution would be write as a BigDecimal instead, converting the value first to a string.

```java
new java.math.BigDecimal(Float.toString(float))
```

A unit test which reproduces the issue
```java
public class EsTest {
@Test
public void knnSerialization() {
var expectedJson = """
{"knn":{"field":"f1","query_vector":[3.1415927,2.7182817,0.501,100.0,1.0E-5]}}""";
Query query1 = QueryBuilders.knn(k -> k
.queryVector(List.of((float) Math.PI, (float) Math.E, 0.501f, 100f, 1e-5f))
.field("f1")
);
String actualJson = JsonpUtils.toJsonString(query1, new JacksonJsonpMapper());
assertThat(actualJson).isEqualTo(expectedJson);
// Expected :"{"knn":{"field":"f1","query_vector":[3.1415927,2.7182817,0.501,100.0,1.0E-5]}}"
// Actual :"{"knn":{"field":"f1","query_vector":[3.1415927410125732,2.7182817459106445,0.5009999871253967,100.0,9.999999747378752E-6]}}"
}
}
```