Fix Socket::close() connection handling

[jasnell]

No description provided.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 87.50000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 70.00%. Comparing base (752ea91) to head (4a97552).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
src/workerd/api/sockets.c++	83.33%	0 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5952      +/-   ##
==========================================
+ Coverage   69.66%   70.00%   +0.33%     
==========================================
  Files         397      406       +9     
  Lines      105999   107104    +1105     
  Branches    17965    17964       -1     
==========================================
+ Hits        73848    74973    +1125     
+ Misses      21358    21336      -22     
- Partials    10793    10795       +2     

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