network: use http.ResponseController instead of GetHTTPRequestConnection

[cce]

Summary

Mentioned in #6042, the network interface has since #1390 required a method GetHTTPRequestConnection so that an HTTP handler could call SetWriteDeadline to set a request-specific write deadline. (It is used for setting a longer write deadline when serving large catchpoint snapshot files.)

In Go 1.20 per-request deadlines were added to the builtin HTTP library using http.ResponseController, which makes it very easy to do from inside a HTTP handler. This makes the connection-tracking middleware in #1390 and #5924 to implement GossipNode.GetHTTPRequestConnection obsolete.

For reviewers: the deleted lines all come from #1390 and #5924, so if you open up those side-by-side you should be able to see what is being removed vs. what is being left.

Test Plan

Existing tests should pass, and maybe a new test should be added to ledgerService_test.go to ensure the write deadlines are working as described when using (http.ResponseController).SetWriteDeadline.

[codecov]

Codecov Report

Attention: Patch coverage is 82.35294% with 3 lines in your changes missing coverage. Please review.

Project coverage is 56.13%. Comparing base (c8407ab) to head (d8c2922).

Files	Patch %	Lines
rpcs/ledgerService.go	57.14%	1 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6044      +/-   ##
==========================================
- Coverage   56.15%   56.13%   -0.03%     
==========================================
  Files         488      488              
  Lines       69532    69425     -107     
==========================================
- Hits        39044    38969      -75     
+ Misses      27832    27804      -28     
+ Partials     2656     2652       -4     

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[algorandskiy]

Nice work