Stop using the Xml class in this codebase

There was only a single caller. Maybe a mistake or just old code
that was never updated.

As well as:
* Avoid the separate open/closeElement when possible, usually in
  favor of a single rawElement.
* Note this patch also fixes one place where a message was added to
  the HTML output without escaping.

Bug: T341775
Change-Id: I51a29b47fbd8e0269c065e4277ef775f1d659ff6
2 files changed