The `querystring-search` endpoint limits the result to 1000 items

[wesleybl]

Describe the bug

When we use the querystring-search endpoint without the limit parameter, it limits the result to 1000 items. However, the who requesting the search doesn't know how many items there are.

To Reproduce

Steps to reproduce the behavior:

1. Create more than 1000 Documents on the Portal and publish.
2. Execute the command:

curl -i -X POST http://localhost:8080/Plone/@querystring-search -H "Accept: application/json" -H "Content-Type: application/json" --data-raw '{"query": [{"i": "portal_type", "o": "plone.app.querystring.operation.selection.any", "v": ["Document"]}]}'

Expected behavior

All documents must be returned.

Software (please complete the following information):

• OS: Ubuntu
• Browser: Chrome
• Plone Version: 6.1.3
• Volto Version: 18.29.0

Additional context

We are having this problem in the Volto lists block.

The limitation occurs here:

https://github.com/plone/plone.restapi/blob/fda897320ee56c258123bc974ed8630573ec5c1e/src/plone/restapi/services/querystringsearch/get.py#L41