Remove the originalMetadataAuthor node from the committed pages, for XWiki 14.5+

The originalMetadataAuthor property was removed from the xar:format in 14.5 (XCOMMONS-2446) but not from the page metadata themselves.
Thus, the code added for ticket XGITLAB-33 will continue to serialize it for commit it for XWiki versions 14.5, making the page incompatible with the result obtained from the formatter (xar:format).

The fix is probably to add an option, like for the dates for XGITLAB-6.

Alternatively we can try to detect the 'right' format otherwise, for example:

• based on the XWiki version - but this can create issues because the configuration from the pom for the xar:format may not be compatible with the 'default' of that version
• actually run xar:format on the file, if the code from the maven plugin is reusable.