[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 91.45%. Comparing base (33264a5) to head (cc4ba46).

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #10996   +/-   ##
=======================================
  Coverage   91.45%   91.45%           
=======================================
  Files         447      447           
  Lines       23721    23727    +6     
=======================================
+ Hits        21694    21700    +6     
  Misses       1653     1653           
  Partials      374      374           

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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

[jpkrohling]

LGTM, however, I feel bad for introducing new features when we are aiming for v1.

If the Collector approvers decide that this is something we should NOT have for v1, I'd be on their side.