EZP-22985: Fixing file uploads with the ezpRelationListAjaxUploader

With [EZP-22480](https://jira.ez.no/browse/EZP-22480)/https://github.com/ezsystems/ezpublish-legacy/commit/b6f895ed1b790039f623d1476c8ffaecc6961080, the creation of node assignments between an uploaded file and the parent node have been extracted from the `publishObject` method to the `handleUpload()` method.

In the same class, the `handleLocalFile()` method also calls the `publishObject()` method, but doesn't add the node assignments part. This causes the relation list Uploader to break when uploading a file directly in to an object relation list from a node.

see https://jira.ez.no/browse/EZP-22985 for the same description but also the steps which should reproduce the issue.

With the patch proposed in this PR, the node assignments parts is added to the `handleLocalFile()` method, similarly to the `handleUpload()` method.

Cheers
:octocat: Jérôme