Json2XmlValidator multi-array in json translate to ugly (yet technically valid) xml

### Current Behavior

With the following json input:
```json
{
"array": [
[
"one",
"two"
],
[
"two",
"three"
],
[
"one",
"three"
]
]
}
```

The current output is:
```xml

one


two


two


three


one


three

```

### Expected Behavior

I would expect:
```xml

one
two


two
three


one
three

```

### Environment Information

7.8+ but this is not something that needs to be backported 😃 .

### Steps To Reproduce

See #7829 and `TestJson2Xml#testMultidimensionalArray()`.