XmlMapper with `FAIL_ON_UNKNOWN_PROPERTIES` fails on whitespace-only element

### Search before asking

- [x] I searched in the [issues](https://github.com/FasterXML/jackson-databind/issues) and found nothing similar.

### Describe the bug

Take this XML:
```xml

```
If I want to deserialize that `Item` element into `record Item(String name)`, I'm faced with this error:
```
Unrecognized property "" (class me.retrodaredevil.randomjunkk.JacksonXmlWhitespaceOnlyContentTest$Item), not marked as ignorable (one known property: "name")
at [No location information] (through reference chain: me.retrodaredevil.randomjunkk.JacksonXmlWhitespaceOnlyContentTest$Response["Item"]->me.retrodaredevil.randomjunkk.JacksonXmlWhitespaceOnlyContentTest$Item[""])
tools.jackson.databind.exc.UnrecognizedPropertyException: Unrecognized property "" (class me.retrodaredevil.randomjunkk.JacksonXmlWhitespaceOnlyContentTest$Item), not marked as ignorable (one known property: "name")
at [No location information] (through reference chain: me.retrodaredevil.randomjunkk.JacksonXmlWhitespaceOnlyContentTest$Response["Item"]->me.retrodaredevil.randomjunkk.JacksonXmlWhitespaceOnlyContentTest$Item[""])
at tools.jackson.databind.exc.UnrecognizedPropertyException.from(UnrecognizedPropertyException.java:53)
at tools.jackson.databind.DeserializationContext.handleUnknownProperty(DeserializationContext.java:1378)
at tools.jackson.databind.deser.std.StdDeserializer.handleUnknownProperty(StdDeserializer.java:2099)
at tools.jackson.databind.deser.bean.BeanDeserializerBase.handleUnknownProperty(BeanDeserializerBase.java:2032)
at tools.jackson.databind.deser.bean.BeanDeserializerBase.handleUnknownProperties(BeanDeserializerBase.java:1957)
at tools.jackson.databind.deser.bean.BeanDeserializer._deserializeUsingPropertyBased(BeanDeserializer.java:922)
at tools.jackson.databind.deser.bean.BeanDeserializerBase.deserializeFromObjectUsingNonDefault(BeanDeserializerBase.java:1695)
at tools.jackson.databind.deser.bean.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:629)
at tools.jackson.databind.deser.bean.BeanDeserializer.deserialize(BeanDeserializer.java:200)
at tools.jackson.databind.deser.SettableBeanProperty.deserialize(SettableBeanProperty.java:568)
at tools.jackson.databind.deser.bean.BeanDeserializer._deserializeWithErrorWrapping(BeanDeserializer.java:943)
at tools.jackson.databind.deser.bean.BeanDeserializer._deserializeUsingPropertyBased(BeanDeserializer.java:775)
at tools.jackson.databind.deser.bean.BeanDeserializerBase.deserializeFromObjectUsingNonDefault(BeanDeserializerBase.java:1695)
at tools.jackson.databind.deser.bean.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:629)
at tools.jackson.databind.deser.bean.BeanDeserializer.deserialize(BeanDeserializer.java:200)
at tools.jackson.dataformat.xml.deser.XmlDeserializationContext.readRootValue(XmlDeserializationContext.java:69)
at tools.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:2666)
at tools.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:1556)
at me.retrodaredevil.randomjunkk.JacksonXmlWhitespaceOnlyContentTest.deserializesWhitespaceOnlyElementContent(JacksonXmlWhitespaceOnlyContentTest.java:27)
```

This is an issue for more complicated XML data, specifically data like this:
```xml

```
I run into this problem because `Item` typically has nested elements inside of it, but when it doesn't, the whitespace data within it is treated as a special blank string property.

### Version Information

Jackson 3.2.1

### Reproduction

```java
import com.fasterxml.jackson.annotation.JsonProperty;
import org.junit.jupiter.api.Test;
import tools.jackson.databind.DeserializationFeature;
import tools.jackson.dataformat.xml.XmlMapper;

import static org.junit.jupiter.api.Assertions.assertEquals;

class JacksonXmlWhitespaceOnlyContentTest {

// This test fails because whitespace-only element content is exposed as an empty-named property.
@Test
void deserializesWhitespaceOnlyElementContent() {
XmlMapper mapper = XmlMapper.builder()
.enable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES)
.build();
String xml = """




""";

Response response = mapper.readValue(xml, Response.class);

assertEquals(new Item("example"), response.item());
}

record Response(
@JsonProperty("Item") Item item
) {
}

record Item(String name) {
}
}
```

### Expected behavior

`FAIL_ON_UNKNOWN_PROPERTIES` should only cause failures when there are actual properties that are unknown. I don't think this weird empty string property edge case should cause a failure here.

### Additional context

_No response_