[FIX] account, account_cancel: visibility of the button_cancel_reconciliation

When a account statement is validated, it's not possible to cancel a statement line.
To cancel a line from a validated statement, you must first reset to new the statement.
In this way, it's not possible to have a validated statement with unreconciled lines.

opw:690766

addons/account/models/account_bank_statement.py

@@ -373,6 +373,7 @@ class AccountBankStatementLine(models.Model):
     journal_entry_ids = fields.One2many('account.move', 'statement_line_id', 'Journal Entries', copy=False, readonly=True)
     amount_currency = fields.Monetary(help="The amount expressed in an optional other currency if it is a multi-currency entry.")
     currency_id = fields.Many2one('res.currency', string='Currency', help="The optional other currency if it is a multi-currency entry.")
+    state = fields.Selection(related='statement_id.state' , string='Status', readonly=True)
 
     @api.one
     @api.constrains('amount')

addons/account_cancel/account_cancel_view.xml

@@ -54,7 +54,8 @@
                     <attribute name="options">{'reload_on_button': true}</attribute>
                 </field>
                 <xpath expr="//field[@name='bank_account_id']" position="after">
-                    <button name="button_cancel_reconciliation" attrs="{'invisible': [('journal_entry_ids', '=', [])]}" string="Cancel" type="object" icon="gtk-undo"/>
+                    <field name="state" invisible="1"/>
+                    <button name="button_cancel_reconciliation" attrs="{'invisible': ['|',('journal_entry_ids', '=', []), ('state', '=', 'confirm')]}" string="Cancel" type="object" icon="gtk-undo"/>
                 </xpath>
             </field>
         </record>