fix: reading file uploads map by ignoring actual indices in map

[devsergiy]

Motivation and Context

Checklist

• I have discussed my proposed changes in an issue and have received approval to proceed.
• I have followed the coding standards of the project.
• Tests or benchmarks have been added or updated.
• Documentation has been updated on https://github.com/wundergraph/cosmo-docs.
• I have read the Contributors Guide.

[github-actions]

Router image scan passed

✅ No security vulnerabilities found in image:

ghcr.io/wundergraph/cosmo/router:sha-13415b795af7d74bb0e1004a18d84d4bb73ca464

[Aenimus]

LGTM