Before this commit, receiving a very long message in a channel scrolled at the bottom could move the message list to the end of that message instead of to its beginning. Every message received afterwards then kept the list at the end. The test "should scroll to bottom on receiving new message if the list is initially scrolled to bottom (asc order)" fails on runbot with:

    10. [toBeGreaterThan] expected value to be strictly greater
    > Minimum: 20762
    > Received: 5190.500

This happens because `applyScroll` also runs outside of a patch, on a resize of the message list or on a loaded image, i.e. while a received message is in the store and not rendered yet. Such a run finds no element for the message, scrolls to the bottom of the list, and records the message as the newest one the scroll was applied on. The patch that renders the message then finds no newer message, and keeps the list at the bottom.

This commit fixes the issue by keeping the newest message `applyScroll` recorded when the first newer message has no element yet, so that the patch that renders the message applies the scroll.

Note that the added test delays the registration of the message element, as a resize cannot be timed between the store update and the patch.

https://runbot.odoo.com/odoo/error/946929

If a client deletes a standard account or tax, its XMLID can no longer be resolved during the post-init hook. In that case, _load_data() may create a new record using only the provided data, e.g.:

```
('l10n_bg_691001', {'l10n_bg_saft_account_code': '624'})
```

This can lead to incorrect records.

Only update records whose XMLIDs still exist, avoiding the creation of new records when the corresponding standard record has been deleted.

```
File "/home/odoo/src/enterprise/19.0/l10n_bg_saft/__init__.py", line 10, in _add_account_saft_code
    Template._load_data({'account.account': Template._get_bg_saft_account_code()})
  File "/tmp/tmpbu1ntr1j/migrations/account/0.0.0/pre-ensure-deferred-accounts.py", line 37, in _load_data
    return super()._load_data(data, *args, **kwargs)
  File "/home/odoo/src/odoo/19.0/addons/account/models/chart_template.py", line 697, in _load_data
    created_records[model] = self.with_context(lang='en_US').env[model]._load_records(all_records_vals)
  File "/home/odoo/src/odoo/19.0/odoo/orm/models.py", line 5196, in _load_records
    records = self._load_records_create([data['values'] for data in to_create])
  File "/home/odoo/src/odoo/19.0/odoo/orm/models.py", line 5103, in _load_records_create
    records = self.create(vals_list)
  File "/home/odoo/src/odoo/19.0/odoo/orm/decorators.py", line 369, in create
    return method(self, vals_list)
  File "/home/odoo/src/odoo/19.0/addons/account/models/account_account.py", line 1055, in create
    )).create(vals_list_for_company)
  File "/home/odoo/src/odoo/19.0/odoo/orm/decorators.py", line 369, in create
    return method(self, vals_list)
  File "/home/odoo/src/odoo/19.0/addons/mail/models/mail_thread.py", line 329, in create
    threads = super(MailThread, self).create(vals_list)
  File "/home/odoo/src/odoo/19.0/odoo/orm/decorators.py", line 369, in create
    return method(self, vals_list)
  File "/tmp/tmpbu1ntr1j/migrations/util/orm.py", line 267, in wrapper
    return f(*args, **kwargs)
  File "/tmp/tmpbu1ntr1j/migrations/base/0.0.0/pre-models-match_uniq.py", line 25, in create
    return super().create(vals_list)
  File "/home/odoo/src/odoo/19.0/odoo/orm/decorators.py", line 369, in create
    return method(self, vals_list)
  File "/home/odoo/src/odoo/19.0/odoo/orm/models.py", line 4711, in create
    records = self._create(data_list)
  File "/home/odoo/src/odoo/19.0/odoo/orm/models.py", line 4887, in _create
    cr.execute(SQL(
  File "/home/odoo/src/odoo/19.0/odoo/sql_db.py", line 440, in execute
    self._obj.execute(query, params)
psycopg2.errors.NotNullViolation: null value in column "account_type" of relation "account_account" violates not-null constraint
DETAIL:  Failing row contains (734, null, 1, 1, null, null, null, t, f, f, 2026-08-25 08:18:15.751937, 2026-08-25 08:18:15.751937, no, f, null, null, null, null, 411).
```

upg-4611390
tbg-2902

Forward-Port-Of: odoo/enterprise#129145