### What problem does this PR solve?
The document metadata cache is built using the list documents endpoint
with default pagination parameters of page=1, page_size=3. This means
when using the MCP server to search a dataset, only chunks which come
from the first 30 documents in the dataset will have metadata returned.
Issue described in more detail here
https://github.com/infiniflow/ragflow/issues/11533
### Type of change
- [x] Bug Fix (non-breaking change which fixes an issue)
Co-authored-by: Giles Lloyd <giles.af.lloyd@gmail.com>
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