tests/xwayland: Enable xwayland XWM debug log scope and more debug

We're still timing out with our basic xwayland test in CI, so this
enables the XWM logging scope, and enables some further print debugs we
have available in our helper library, in an attempt to further
investigate and determine why we're still timing out.

Signed-off-by: Marius Vlad <marius.vlad@collabora.com>