p2p: fix connection deduplication in hybrid mode

[algorandskiy]

Summary

Some TestHybridNetwork_DuplicateConn failures indicate deduplication does not work when a node first connects via wsnet and then via p2p. In this case p2p correctly determines duplicate but does not exit the handler as it should.

Test Plan

Added a unit test checking the stream handler processes duplication correctly.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 56.27%. Comparing base (2b34eda) to head (87e8ea3).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #6082   +/-   ##
=======================================
  Coverage   56.27%   56.27%           
=======================================
  Files         488      488           
  Lines       69587    69588    +1     
=======================================
+ Hits        39157    39161    +4     
+ Misses      27771    27769    -2     
+ Partials     2659     2658    -1     

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