fix: remove body validation from unclean termination

[rvagg]

While doing #386 I discovered that Go's HTTP client, once it discovers an unclean end, will immediately decide that the body shouldn't be read. So you have up until the moment of it discovering the unclean end to read the body, after that point you get an EOF.

I wish I saved the Go src where I found this, it might be worth me going back and finding it to confirm that I'm talking sense here.

I believe this explains occasional flakies like this one: https://github.com/filecoin-project/lassie/actions/runs/5960306260/job/16167386428?pr=383

The answer is to just not bother attempting to validate bodies in our integration tests when it's an unclean end. I kind of wish it were different because we do want to validate this, but without the ability to control timing, or change this behaviour, I don't believe we can.

[rvagg]

backburner for the immediate term, I just need to validate what's actually happening here because of a small amount of uncertainty because the internal body reader shouldn't encounter the problem while you're streaming data out until it reached the bad chunk, so it probably depends on Read size inside the body reader; I just need to check that and confirm I'm not missing something or that there's an alternative thing/way to test here.

[rvagg]

https://github.com/filecoin-project/lassie/actions/runs/6069733198/job/16464569544?pr=406

https://github.com/filecoin-project/lassie/actions/runs/6078212150/job/16489094536

[codecov-commenter]

Codecov Report

Merging #398 (e1aaca9) into rvagg/trustless-utils (1129833) will increase coverage by 0.27%.
Report is 1 commits behind head on rvagg/trustless-utils.
The diff coverage is n/a.

Additional details and impacted files

@@                    Coverage Diff                    @@
##           rvagg/trustless-utils     #398      +/-   ##
=========================================================
+ Coverage                  76.28%   76.55%   +0.27%     
=========================================================
  Files                         85       85              
  Lines                       6296     6296              
=========================================================
+ Hits                        4803     4820      +17     
+ Misses                      1244     1231      -13     
+ Partials                     249      245       -4     

see 7 files with indirect coverage changes

[rvagg]

I think this is as good as it's going to get - instead of removing the body validation, this does more careful body slurping, inching up to the expected error so we get the full body and the error. Seems to be good, after many CI reruns.