[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 91.59%. Comparing base (9c4c007) to head (2f02614).

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #10996   +/-   ##
=======================================
  Coverage   91.58%   91.59%           
=======================================
  Files         440      440           
  Lines       23765    23771    +6     
=======================================
+ Hits        21766    21772    +6     
  Misses       1627     1627           
  Partials      372      372           

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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]

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