Use .on and .off for unexpected-response listener

[KyleBoyer]

The unexpected-response listener needs to use .on and .off because the ws package's addEventListener only accepts certain event types
Ref: https://github.com/websockets/ws/blob/8.16.0/lib/event-target.js#L202-L241

Additionally PR #2936 had slightly different logic for the body chunk return, so I have updated that here too.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.05%. Comparing base (cfd6889) to head (b138092).
Report is 62 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #2969      +/-   ##
============================================
+ Coverage     77.87%   78.05%   +0.18%     
- Complexity    13578    13885     +307     
============================================
  Files          1015     1019       +4     
  Lines         59308    59819     +511     
  Branches       6835     6926      +91     
============================================
+ Hits          46184    46690     +506     
+ Misses        10817    10806      -11     
- Partials       2307     2323      +16     

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[kenhuuu]

Thanks again for contributing and for catching these issues from the merge.

VOTE +1

[KyleBoyer]

@kenhuuu is this good to merge? 😁