transport: add test case for zero second timeout

[dfawley]

(This includes the fix in #8451 in order to make the test not hang.)

RELEASE NOTES: none

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 82.35%. Comparing base (bed551a) to head (fbee081).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8452      +/-   ##
==========================================
- Coverage   82.40%   82.35%   -0.06%     
==========================================
  Files         414      414              
  Lines       40436    40437       +1     
==========================================
- Hits        33322    33302      -20     
- Misses       5757     5775      +18     
- Partials     1357     1360       +3     

Files with missing lines	Coverage Δ
internal/transport/http2_server.go	91.14% <100.00%> (+1.54%)	⬆️

... and 23 files with indirect coverage changes

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