Fix missing http2 connection info

[rafaelroquetto]

Golang can upgrade an SSL connection from HTTP1.1 to HTTP2 if the server supports it. We were missing a probe and offsets information for the vendored Go http2 functions to be able to fetch the connection information properly.

Closes #1430

(This is a rebase of the original PR: #1461)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.11%. Comparing base (0d8cdc3) to head (b7a3c42).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1464      +/-   ##
==========================================
- Coverage   81.17%   81.11%   -0.06%     
==========================================
  Files         149      149              
  Lines       15339    15342       +3     
==========================================
- Hits        12451    12445       -6     
- Misses       2274     2280       +6     
- Partials      614      617       +3     

Flag	Coverage Δ
integration-test	59.67% <100.00%> (-0.01%)	⬇️
k8s-integration-test	60.55% <100.00%> (-0.15%)	⬇️
oats-test	33.82% <100.00%> (+0.01%)	⬆️
unittests	51.79% <0.00%> (-0.02%)	⬇️

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