When a record is created through xml data, its HTML fields should
receive a `type="html"` attribute, not a `type="xml"` attribute.
When important XML data with XML type instead of HTML type will have 2
differences:
- The field value will be prefixed by `<?xml version="1.0"/>`
- If the HTML contains multiple root nodes, the value will be wrapped in
a `<data/>` tag.
See `_fix_multiple_roots()` and the `xml_import` class for more details.
closesodoo/odoo#98239
Related: odoo/enterprise#30491
Signed-off-by: Xavier Morel (xmo) <xmo@odoo.com>