Before this commit, the code of the `add_to_dashboard` method did not go
through the get_view override of the board model. Because of that, it
did not get the arch of the current board, which means that each
add_to_dashboard call was actually a complete reset: it was not possible
to add an action without removing the current board state.
For reference, this was caused recently by a change in commit b03c227e88.
The fix is basically a localized revert of that commit.
closesodoo/odoo#90830
Signed-off-by: Denis Ledoux (dle) <dle@odoo.com>