Primary and link buttons are "hacked" by mailing themes scss. We thus
have to fix their preview if possible (as they are previewed as standard
bootstrap while they actually have a different look depending on the
mailing theme).
Note: this commit is obviously a big hack which calls for lots of
improvements in master.
FIXME: this only partially work due to the new editor, it has to be
fixed as soon as the master becomes stable again...
Part of https://github.com/odoo/odoo/pull/60308
opw-2360756
X-original-commit: 7bd7bc2513b72f5ffc006758c4bf4eb42ae6ed67
qsm-odoo
6ce28c29db