[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 91.47%. Comparing base (52e11ec) to head (6bb2a59).

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #10996   +/-   ##
=======================================
  Coverage   91.47%   91.47%           
=======================================
  Files         424      424           
  Lines       20206    20211    +5     
=======================================
+ Hits        18484    18489    +5     
  Misses       1339     1339           
  Partials      383      383           

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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?