Changelog for switching periodreader default

[cijothomas]

Code changes not yet in, just seeing how the changelog would look like and get some feedback.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.3%. Comparing base (902baa9) to head (edff359).

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #2399   +/-   ##
=====================================
  Coverage   79.3%   79.3%           
=====================================
  Files        123     123           
  Lines      21566   21566           
=====================================
  Hits       17112   17112           
  Misses      4454    4454           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[cijothomas]

OTLP Exporter has to default to HTTP and should use request-blocking client as default for this to work.
Add a todo here, to talk about what the user should be doing if they need to use tonic, similar to comments from #2394

[cijothomas]

Closing in favor of #2403