[REF] account_check_printing: Speed-up payment creation

The method constraint to validate the Check Number is slow

1. Analyzing the following query:

```sql
SELECT
    payment.check_number,
    move.journal_id
FROM
    account_payment payment
    JOIN account_move move ON move.id = payment.move_id
    JOIN account_journal journal ON journal.id = move.journal_id,
    account_payment other_payment
    JOIN account_move other_move ON other_move.id = other_payment.move_id
WHERE
    payment.check_number::integer = other_payment.check_number::integer
    AND move.journal_id = other_move.journal_id
    AND payment.id != other_payment.id
    AND payment.id IN (1085159)
    AND move.state = 'posted'
    AND other_move.state = 'posted';
```

The output is:

    Planning Time: 3.354 ms
    Execution Time: 2514.660 ms

Discarding null values

```diff
    AND other_move.state = 'posted';
+    AND payment.check_number IS NOT NULL
+    AND other_payment.check_number IS NOT NULL
```

The output is

    Planning Time: 3.216 ms
    Execution Time: 0.140 ms

2. The constraint is computed even if the payment is not a check (check_number is empty)

Returning early save useless extra computating
It is not needed to compare falsy values for duplicated for whole table

3. The validation to check is it not a number is not optimal

It is transforming the string -> integer -> string to check if the string is not a number
but it is enough using only string -> integer not needed to transform to string again

    python3 -m timeit -u msec -s "check_numbers = [str(i) for i in range(1000000)]" "[str(int(i)) for i in check_numbers]"
        > 1 loop, best of 5: 323 msec per loop

    python3 -m timeit -u msec -s "check_numbers = [str(i) for i in range(1000000)]" "[int(i) for i in check_numbers]"
        > 2 loops, best of 5: 135 msec per loop

It is better but not enough, using `str.isdigit` method is 5x faster than original approach

    python3 -m timeit -u msec -s "check_numbers = [str(i) for i in range(1000000)]" "[i.isdecimal() for i in check_numbers]"
        > 5 loops, best of 5: 64 msec per loop

closes odoo/odoo#83851

X-original-commit: 31e0ed8c957e8a6af7f6bd5d449b450967206eab
Signed-off-by: Olivier Colson <oco@odoo.com>

addons/account_check_printing/models/account_payment.py

@@ -46,12 +46,12 @@ class AccountPayment(models.Model):
 
     @api.constrains('check_number', 'journal_id')
     def _constrains_check_number(self):
-        if not self:
+        payment_checks = self.filtered('check_number')
+        if not payment_checks:
             return
-        try:
-            self.mapped(lambda p: str(int(p.check_number)))
-        except ValueError:
-            raise ValidationError(_('Check numbers can only consist of digits'))
+        for payment_check in payment_checks:
+            if not payment_check.check_number.isdecimal():
+                raise ValidationError(_('Check numbers can only consist of digits'))
         self.flush()
         self.env.cr.execute("""
             SELECT payment.check_number, move.journal_id
@@ -66,8 +66,10 @@ class AccountPayment(models.Model):
                AND payment.id IN %(ids)s
                AND move.state = 'posted'
                AND other_move.state = 'posted'
+               AND payment.check_number IS NOT NULL
+               AND other_payment.check_number IS NOT NULL
         """, {
-            'ids': tuple(self.ids),
+            'ids': tuple(payment_checks.ids),
         })
         res = self.env.cr.dictfetchall()
         if res: