Custom site.yaml blueprint doesn't support more than one fieldset

I have a `user/blueprints/config/site.yaml` file with a single fieldset that was working as expected. With the snippet below, the **Location Services** fieldset is rendered with the correct fields:

```
accessconfirm:
type: markdown
label: 'Accessibility form confirmation message'
rfpconfirm:
type: markdown
label: 'RFP form confirmation message'

fieldset:
type: fieldset
title: 'Location Services'
text: 'The text and images below are used across Location pages where provided.'
collapsed: true
collapsible: true
fields:
photos:
label: 'Service Images'
type: file
destination: 'user/images/location/services'
multiple: true
accept:
- image/*
```

When I added another fieldset before this one, the new one appeared but the existing **Location Services** fieldset was no longer rendered. With the snippet below, the **Form Configuration** fieldset appears but the **Location Services** fieldset does not:

```
whyworkwithus:
type: textarea
label: 'Why Work with Us?'
fieldset:
type: fieldset
title: 'Form Configuration'
text: 'Customizing the Contact and other forms.'
collapsed: true
collapsible: true
fields:
contactconfirm:
type: markdown
label: 'Contact form confirmation message'
applyconfirm:
type: markdown
label: 'Application form confirmation message'
accessconfirm:
type: markdown
label: 'Accessibility form confirmation message'
rfpconfirm:
type: markdown
label: 'RFP form confirmation message'

fieldset:
type: fieldset
title: 'Location Services'
text: 'The text and images below are used across Location pages where provided.'
collapsed: true
collapsible: true
fields:
photos:
label: 'Service Images'
type: file
destination: 'user/images/location/services'
multiple: true
accept:
- image/*
```

Start with user/blueprints/config/site.yaml and reproduce the configuration with two fieldset entries. Inspect the Grav Form plugin's blueprint parsing and rendering entry points to determine why only one fieldset appears. Done means both the Form Configuration and Location Services fieldsets render with their fields.

Written by the indexing model from the issue text.