fix(instrumentation-http): resume responses when there is no response…

[dyladan]

Fixes #4316

There is a memory leak in node 20 which is a manifestation of a problem that has been around for a while. If a user makes an http request and doesn't add a response listener to the request, the response body is typically dropped by the node runtime. The HTTP instrumentation adds a listener, which prevents the runtime from dropping the body. We should resume the response in order to put the stream back into flowing mode, which will cause the runtime to have the correct behavior after our callback returns.

This is fixed in the next branch by #4331 but if this merges first I will remove it from there.

[codecov]

Codecov Report

Merging #4332 (3f96f1f) into main (f654636) will increase coverage by 0.00%.
The diff coverage is 100.00%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4332   +/-   ##
=======================================
  Coverage   92.31%   92.31%           
=======================================
  Files         330      330           
  Lines        9424     9426    +2     
  Branches     1998     1999    +1     
=======================================
+ Hits         8700     8702    +2     
  Misses        724      724           

Files	Coverage Δ
...ges/opentelemetry-instrumentation-http/src/http.ts	93.35% <100.00%> (+0.04%)	⬆️

[Flarna]

Well, it's actually not a leak in node.js and it's not new in node.js 20.
Caller is responsible to consume the data according to docs.
Instrumentation adds a response listener and this avoids the automatic data discard. So it's the instrumentation which causes the leak here in case user doesn't set a response listener and consumes the data. Data is kept in the incoming socket queue.

The reason why this was hidden in node 18 is that node 20 uses connection keep alive on default. As a result the socked data queue got more and more data.