[otlphttpreceiver] Allow H2C connections to otlp http receiver

[iblancasa]

Description

Allow H2C connections to otlp http receiver

Fixes #10952

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.15%. Comparing base (a7d019f) to head (245cac2).

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #10996   +/-   ##
=======================================
  Coverage   92.15%   92.15%           
=======================================
  Files         432      432           
  Lines       20253    20258    +5     
=======================================
+ Hits        18664    18669    +5     
  Misses       1228     1228           
  Partials      361      361           

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[iblancasa]

@djaglowski could you take a look?

[jpkrohling]

I believe this should be opt-in, and have a log warning stating that this is a "weird" configuration. Only very specific setups have a valid reason to have this enabled, such as sidecars terminating TLS right before handing over to the main container.

[iblancasa]

Is there anything else pending from this PR?

[iblancasa]

Can somebody from @open-telemetry/collector-approvers take a look? Thank you