Router Fails to Validate HTTP Body Length Before Sending to Coprocessor Plugin

[rafaelreinert]

Describe the bug

When body length is less than the 'Content-Length' header instead of ignoring or correctly log the request, router throws an exception on https://github.com/apollographql/router/blob/dev/apollo-router/src/services/router/body.rs#L92, logging the misleading message:

error: external extensibility: router request stage error: error reading a body from connection: error reading a body from connection: error reading a body from connection: error reading a body from connection: end of file before message length reached

I spent some hours to figure it out that the issue was not related the my coprocessor.

To Reproduce

1. Setup Router + Coprocessor for router request.
2. Submit request without body but the Content-Length
3. See external extensibility error and others.

Expected behavior

Validate the request before and send correct log.