Combination of Form Pages and repeating_subfields do not work properly in edit mode.

using form pages repeating_subfields causes inconsistency. While adding a new resource works perfectly, for editing the resource, it does not work for those fields with repeating_subfields. The main problem is that the repeating subfields only take the initial value (can be also empty) and after editing the new values do not update.

to reproduce the error:
ckan version: 2.10
ckanext-scheming: latest (installed on 01.07.2023)
scheming.yml -> Try to add one organization and date when creating a new dataset, and then edit these same fields with a new organization and date

```
scheming_version: 2
dataset_type: test
about_url: http://example.com/the-camel-photos-schema

dataset_fields:

- start_form_page:
title: Basic Info
description: Required and core dataset fields

field_name: title
label: Title
preset: title
form_placeholder: eg. A descriptive title

- field_name: name
label: URL
preset: dataset_slug
form_placeholder: eg. my-dataset

- field_name: notes
label: Description
form_snippet: markdown.html
form_placeholder: eg. Some useful notes about the data

- field_name: owner_org
label: Organization
preset: dataset_organization

- start_form_page:
title: Detailed Info
description:
These fields improve search and give users important links

field_name: tag_string
label: Tags
preset: tag_string_autocomplete
form_placeholder: eg. economy, mental health, government

- field_name: citation
label: Citation
repeating_subfields:
- field_name: originator
label: Originator
preset: multiple_text
form_blanks: 3
required: true
- field_name: publication_date
label: Publication Date
preset: date
- field_name: online_linkage
label: Online Linkage
preset: multiple_text
form_blanks: 2

resource_fields:

- field_name: url
label: URL
preset: resource_url_upload

- field_name: name
label: Name
form_placeholder: eg. January 2011 Gold Prices

- field_name: description
label: Description
form_snippet: markdown.html
form_placeholder: Some useful notes about the data

- field_name: format
label: Format
preset: resource_format_autocomplete
```

Reproduce the issue in CKAN 2.10 with the provided scheming.yml, creating and then editing a dataset containing the organization, date, and citation repeating_subfields. Start by tracing how ckanext-scheming handles form pages and repeating_subfields during edit mode. Done means edited values persist instead of reverting to their initial or empty values.

Written by the indexing model from the issue text.