Before this commit
==================
Modifying the type of content from video to webpage or webpage to video
violates the constraint.
Technical
=========
When we change the 'slide_type' of the slide.slide model from video to any
other type, or from webpage to any other type, the value url or html_content
is not removed and remains same. However, when switching between video and
webpage, the 'exclusion_html_content_and_url' constraint is violated because one
of them should be null.
After this commit
=================
When the type of content is changed, the existing URL or HTML content is
removed as they are no longer needed.
Task-3474466
closesodoo/odoo#144042
X-original-commit: b68d2f52e9d3d0f18257a17dc1a24db6bee860b1
Signed-off-by: Stéphane Debauche (std) <std@odoo.com>