[IMP] sale_timesheet: change _get_not_billed to _is_not_billed method

Before this commit, we use the _get_not_billed method to get all
timesheets not billed. But in each using, we call the method after a
filtered method.

This commit changes the method to use this method wiht only one
recordset in the self and rename the method to _is_not_billed. This
change allows to avoid the succesive filtered to get the timesheets that
we want. Now, we can use the _is_not_billed method in the first
filtered rathan than realize another filter.

task-2424382

addons/sale_timesheet/models/account.py

@@ -43,11 +43,12 @@ class AccountAnalyticLine(models.Model):
 
     @api.depends('task_id.sale_line_id', 'project_id.sale_line_id', 'employee_id', 'project_id.allow_billable')
     def _compute_so_line(self):
-        for timesheet in self.filtered(lambda t: not t.is_so_line_edited)._get_not_billed():  # Get only the timesheets are not yet invoiced
+        for timesheet in self.filtered(lambda t: not t.is_so_line_edited and t._is_not_billed()):  # Get only the timesheets are not yet invoiced
             timesheet.so_line = timesheet.project_id.allow_billable and timesheet._timesheet_determine_sale_line(timesheet.task_id, timesheet.employee_id, timesheet.project_id)
 
-    def _get_not_billed(self):
-        return self.filtered(lambda t: not t.timesheet_invoice_id or t.timesheet_invoice_id.state == 'cancel')
+    def _is_not_billed(self):
+        self.ensure_one()
+        return not self.timesheet_invoice_id or self.timesheet_invoice_id.state == 'cancel'
 
     def _check_timesheet_can_be_billed(self):
         return self.so_line in self.project_id.mapped('sale_line_employee_ids.sale_line_id') | self.task_id.sale_line_id | self.project_id.sale_line_id

addons/sale_timesheet/models/project.py

@@ -110,7 +110,7 @@ class Project(models.Model):
 
     def _update_timesheets_sale_line_id(self):
         for project in self.filtered(lambda p: p.allow_billable and p.allow_timesheets):
-            timesheet_ids = project.sudo(False).mapped('timesheet_ids').filtered(lambda t: not t.is_so_line_edited)._get_not_billed()
+            timesheet_ids = project.sudo(False).mapped('timesheet_ids').filtered(lambda t: not t.is_so_line_edited and t._is_not_billed())
             if not timesheet_ids:
                 continue
             for employee_id in project.sale_line_employee_ids.filtered(lambda l: l.project_id == project).employee_id: