fix: Add feature flag to otel-http crate to better reflect purpose

[cijothomas]

OTLP was enabling feature flag "request" in otel-http which did not exist! This adds feature flags to the otel-http crate corresponding to the client being used.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.5%. Comparing base (bbb1821) to head (aba40d7).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #3112   +/-   ##
=====================================
  Coverage   80.5%   80.5%           
=====================================
  Files        126     126           
  Lines      22218   22218           
=====================================
  Hits       17889   17889           
  Misses      4329    4329           

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