Enable Netty HTTP header validation

[msaroufim]

Solves
https://github.com/pytorch/serve/security/code-scanning/5
https://github.com/pytorch/serve/security/code-scanning/6
https://github.com/pytorch/serve/security/code-scanning/8
https://github.com/pytorch/serve/security/code-scanning/9

[codecov]

Codecov Report

Merging #2630 (728afb1) into master (d8a1146) will decrease coverage by 0.11%.
Report is 1 commits behind head on master.
The diff coverage is n/a.

❗ Current head 728afb1 differs from pull request most recent head 6f83d44. Consider uploading reports for the commit 6f83d44 to get more accurate results

@@            Coverage Diff             @@
##           master    #2630      +/-   ##
==========================================
- Coverage   71.34%   71.24%   -0.11%     
==========================================
  Files          85       85              
  Lines        3905     3905              
  Branches       58       58              
==========================================
- Hits         2786     2782       -4     
- Misses       1115     1119       +4     
  Partials        4        4              

see 2 files with indirect coverage changes

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more

[lxning]

I'm not sure if there is a history reason of setting false at beginning. I suggest making it configurable (default: true) to avoid breaking some cx prod.

[msaroufim]

Would be nice to have sanity checks in CI for what sagemaker might do but regardless I opened this issue to follow up on later #2639 - would be great if someone wants to pick this up