Stream test results without batched loads into server memory

[ayazhafiz]

Prior to this commit, an ABQ server would always load test results into memory before streaming them to the client. This could result in DOS of the server.

In this patch, we instead stream the results file to the client, but without loading the results into memory. At a given time, at most 8KB of a results file will be loaded in the server memory.

Note that the client still must load all results into memory, and can still suffer a DOS.

[github-actions]

✅ Bigtest for e8cbf0c (run)

Benchmarks:

• RSpec: 10.57% overhead
  • RSpec time: 17.79 seconds
  • ABQ time: 19.67 seconds
• RSpec parallel, 10 runs: max 15.85% overhead
  • min 8.49% overhead
  • standard deviation: 2.11%
• Jest: 5.75% overhead
  • Jest time: 20.352 seconds
  • ABQ time: 21.522 seconds

Fuzz result sizes:

• PASSED