Before this commit, when uploading an attachment then delete
then re-upload attachment again, the reupload was unsuccessful.

This happens because it should clear the `<input>` of type `file`,
but the condition was wrong and therefore `<input>` was not cleared,
thus keeping same value as before so input was not detected as
changed. A change on this file input is necessary to detect user
interaction file upload.

This commit fixes trigger for clearing the `<input>` of type file,
so that any file upload is properly detected, including uploading
same attachment.

Task-3060429

closes odoo/odoo#105422

Signed-off-by: Alexandre Kühn (aku) <aku@odoo.com>