ENG-17140 Ensure requests can be filtered because of method body

[bradAtTraceable]

Description

Please include a summary of the change, motivation and context.

Testing

Please describe the tests that you ran to verify your changes. Please summarize what did you test and what needs to be tested e.g. deployed and tested helm chart locally.

Checklist:

• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• Any dependent changes have been merged and published in downstream modules

Documentation

Make sure that you have documented corresponding changes in this repository or hypertrace docs repo if required.

[bradAtTraceable]

The purpose of this test is to ensure that the Filter receives the contents of an HTTP request body, so that it can block the request, if required. Previously, the request body was only being passed to the filter if the reader of the request body received an indication that the end-of-stream was reached. However, in some cases, the reader would stop reading the request body without seeing the normal end-of-stream indication, and the filter would not be called.

[shashank11p]

@bradAtTraceable Some smoke tests are failing. Please update the tests as well :)