transport: http2 server must validates header list size when early aborting stream

[joybestourous]

Modifies earlyAbortStreamHandler to include check the header list size when early aborting, and returns a RST_STREAM if the max size is exceeded.

Fixes https://github.com/grpc/grpc-go/issues/8766

RELEASE NOTES:

• transport: http2 server now validates header list size when early aborting stream

[codecov[bot]]

Codecov Report

:x: Patch coverage is 89.36170% with 5 lines in your changes missing coverage. Please review. :white_check_mark: Project coverage is 83.39%. Comparing base (489f1f6) to head (2ceced5). :warning: Report is 3 commits behind head on master.

Files with missing lines	Patch %	Lines
internal/transport/http2_server.go	94.87%	1 Missing and 1 partial :warning:
test/servertester.go	71.42%	1 Missing and 1 partial :warning:
internal/transport/controlbuf.go	0.00%	0 Missing and 1 partial :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8769      +/-   ##
==========================================
- Coverage   83.42%   83.39%   -0.03%     
==========================================
  Files         419      419              
  Lines       32556    32578      +22     
==========================================
+ Hits        27161    27170       +9     
- Misses       4015     4031      +16     
+ Partials     1380     1377       -3     

Files with missing lines	Coverage Δ
internal/transport/controlbuf.go	88.93% <0.00%> (+0.31%)	:arrow_up:
internal/transport/http2_server.go	90.97% <94.87%> (-0.11%)	:arrow_down:
test/servertester.go	61.67% <71.42%> (-0.44%)	:arrow_down:

... and 27 files with indirect coverage changes

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[easwars]

@eshitachandwani: I'm moving this to @arjan-bal for second review as he was the one who filed the issue in the first place.