[IMP] partner_statement: remove "blocked" feature

If someone comes from v17 or older Odoo versions, and they still have "blocked" lines, there are three options for them:

- Develop glue module with another module that contains "blocked" field.
- Don't use this commit.
- Solve the "blocked" lines.

Good luck!

partner_statement/__init__.py

@@ -1,5 +1,4 @@
 # License AGPL-3.0 or later (https://www.gnu.org/licenses/agpl.html).
 
-from . import models
 from . import report
 from . import wizard