BI-2941: Increase proxy upload size limit

[humsika]

Summary

Increased the Nginx reverse proxy upload limit from 100M to 1G.

Reason

Genotype VCF files larger than 100 MB were being rejected by biproxy with a 413 Request Entity Too Large response before the request reached bi-api.

The backend supports VCF files up to 800 MB, so the proxy limit was increased to 1 GB to allow for multipart request overhead while keeping the backend as the actual file-size enforcement layer.

Validation

• Confirmed the QA proxy logs showed:
  client intended to send too large body
• Confirmed the active proxy configuration was:
  client_max_body_size 100M;
• Updated proxy/biproxy.docker to:
  client_max_body_size 1G;