Prior to this commit, the default stage didn't follow the value of the
display project id as the project_id was only updated after the write
call.
This commit makes the project_id to be updated after the display
project id changes.
This allows the default stage to be updated too once the onchange is
done.
Tests
---------------
This commit changes the behavior of a test making the use case more
smooth.
Previously, when a user removed both display project id and parent id
from a subtask, the project id was set to False. Now, if the display
project id is removed, the project id goes back to parent project, and
when the parent is set to False, it doesn't affect the display project.
PR: #50576
task-2522066
closesodoo/odoo#71029
X-original-commit: a908b9e8e6577bb7f8c8769db730c855fcad9504
Signed-off-by: LTU-Odoo <IT-Ideas@users.noreply.github.com>