The `loading="lazy"` attribute was set by default on all images but this
affected the `mass_mailing` module as well while that attribute doesn't
work in emails and can cause some issues in edition.
One known such issue this addresses is to be reproduced as follows:
1. Create a new mail
2. Drop the "cover" snippet
It has height 0 so it won't load until another snippet (with a non-zero
height) is dropped.
task-2761074
closesodoo/odoo#84415
Signed-off-by: David Monjoie (dmo) <dmo@odoo.com>
Antoine Guenet
b822da476e