[IMP] odoo: prevent unsafe import from file

It's possible to specify an existing module as the xml id prefix when
importing records from a file. This will result in `ir_module_data`
records being created with `noupdate` set to False. When the module is
upgraded, these records will be deleted.

This can lead to undesired side effects like journal items for
accounts imported this way being deleted.

This change prevents creating new records linked to existing modules
when importing from a file. Instead, the user should either use no
prefix or the name of a non-existent module, like `__import__`.

opw-3231987

closes odoo/odoo#130825

Signed-off-by: Merel Geens <mege@odoo.com>