Original PR description

It currently deleted the inner mail.message, while it should actually remove mail.mail records. Removing messages is managed at mail.mail unlink level using the 'is_notification' field. Indeed a mass_mailing email should remove the linked mail.message, while a canceled notification email should not remove the chatter message.

Followup of odoo/odoo#209494

Forward-Port-Of: odoo/odoo#278321
Forward-Port-Of: odoo/odoo#277993

Original PR description

Currentyl the unsupported models will be checked like the following
```sql
    ia.res_model NOT IN ARRAY['model1', 'model2']
```

This causes a syntax error. Use `ANY` to avoid the issue
```sql
    ia.res_model != ANY(ARRAY['model1', 'model2'])
```

Reproduce in Odoo shell
```python
from odoo.tools import SQL
query = SQL("""
    SELECT ia.id
    FROM ir_attachment ia
    WHERE ia.res_model NOT IN %(unsupported_models)s
    LIMIT 1;
""",
    unsupported_models=self.env['ir.attachment']._get_cloud_storage_unsupported_models(),
)
```

opw-6404861

Forward-Port-Of: odoo/odoo#277971

Original PR description

Steps to reproduce
==================
- Log in with the portal user (or any user without karma points).
- Open a forum post.
- Try to mark it as the best answer.

Technical
=========
From here https://github.com/odoo/odoo/pull/215145/changes/46e5ab20cb33536f0cf12d2fc3690beaa11697ee `htmlJoin` expects its first argument to be an iterable and its second argument separator to be a string. Passing the message string as the first argument causes it to be treated as an iterable of characters, while the guideline markup passed as the second argument is unintentionally used as the separator. As a result, the guideline link is inserted between every character of the message instead of being appended after it.

Wrap the message and the additional guideline text in an array when calling `htmlJoin` so the notification is rendered correctly.

Task-6302585

Forward-Port-Of: odoo/odoo#276137

Original PR description

Because of this PR https://github.com/odoo/odoo/pull/235719 Audit Trail no longer functions as expected:
1) Tracking messages no longer show in the Audit Trail
2) Description is missing from Audit Trail

This commit fixes these issues.

task-6413110

Forward-Port-Of: odoo/odoo#278099