XWiki.parseContent is a leftover method that on one side says it only parses velocity code, but in reality it delegates to the old rendering which runs all the old renderers on the passed content, this includes velocity, groovy and 1.0 syntax.
Thus, we should deprecate it and use the individual rendering/parsing options based on what we want:
- #evaluate(...) for velocity code
- $services.rendering.parse/render for wiki syntaxes
- $xwiki.parseGroovyFromString() for groovy