Remove xml-apis managed dependency

[philwebb]

See #7554 (comment)

[snicoll]

Unfortunately, Htmlunit extends directly from a type provided by xml-apis in DomElement

We should exclude xerces altogether here if we want to exclude xml-apis (if that kicks in, it really need xml-apis). Unfortunately, there's no much we can do at this point.

[snicoll]

I've opened a feature request

[wilkinsona]

Looks like HTMLUnit should work without this now as DomElement no longer implements ElementTraversal.