network: remove ws net proto 2.1

[algorandskiy]

Summary

Remove wsnet proto=2.1 and optional compression since the entire network supports 2.2 and compressed PP messages.
I left couple commented out lines showing how to set and check features.

Test Plan

Existing tests

[codecov]

Codecov Report

Attention: Patch coverage is 80.00000% with 4 lines in your changes missing coverage. Please review.

Project coverage is 56.23%. Comparing base (a9c2b7e) to head (39bc6c7).
Report is 10 commits behind head on master.

Files	Patch %	Lines
network/msgCompressor.go	71.42%	1 Missing and 1 partial ⚠️
network/wsNetwork.go	77.77%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6081      +/-   ##
==========================================
- Coverage   56.26%   56.23%   -0.04%     
==========================================
  Files         488      488              
  Lines       69607    69561      -46     
==========================================
- Hits        39166    39119      -47     
+ Misses      27783    27782       -1     
- Partials     2658     2660       +2     

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[gmalouf]

Looks good overall, asked a few questions.