amp-form - render all submit-error and submit-success nodes of the form

### Description

currently an amp-form only renders the first html node within the tag that contains the attribute "submit-error".

it would be great if every node in the form with existing "submit-error" attribute could be rendered.

example:
```

```

In this example only the first node is ever considered after submit of the form and the second is never rendered, even if the error response contains both properties "phone_duplicate" and "phone" or only the second one "phone_duplicate".

### Alternatives Considered

none

### Additional Context

_No response_

Start at the amp-form entry point that handles submit-error and submit-success nodes, then trace how the first matching node is selected after a response. Verify the behavior with the provided form containing multiple nodes and confirm that every matching node is rendered when its response data applies.

Written by the indexing model from the issue text.