[FIX] mrp, mrp_subcontracting: traceback during unistall

The unlink fail in __init__.py uninstall hook is managed, however
when it fail, the error is catch but the cursor is not rollback and
do not accept additional transaction. That result in a traceback at
uninstall.

opw-2453939

closes odoo/odoo#66278

Signed-off-by: Arnold Moyaux <amoyaux@users.noreply.github.com>