Move PinotRelExchangeType back to the original package to fix backward compatibility

[Jackie-Jiang]

For the reason described in #12934, we cannot move the class serialized in the query plan
Revert the package move of PinotRelExchangeType in #12837

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 62.22%. Comparing base (59551e4) to head (188d920).
Report is 2431 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #12944      +/-   ##
============================================
+ Coverage     61.75%   62.22%   +0.47%     
+ Complexity      207      198       -9     
============================================
  Files          2436     2502      +66     
  Lines        133233   136458    +3225     
  Branches      20636    21117     +481     
============================================
+ Hits          82274    84916    +2642     
- Misses        44911    45261     +350     
- Partials       6048     6281     +233     

Flag	Coverage Δ
custom-integration1	<0.01% <ø> (-0.01%)	⬇️
integration	<0.01% <ø> (-0.01%)	⬇️
integration1	<0.01% <ø> (-0.01%)	⬇️
integration2	0.00% <ø> (ø)
java-11	62.15% <ø> (+0.44%)	⬆️
java-21	62.10% <ø> (+0.48%)	⬆️
skip-bytebuffers-false	62.21% <ø> (+0.47%)	⬆️
skip-bytebuffers-true	34.98% <ø> (+7.25%)	⬆️
temurin	62.22% <ø> (+0.47%)	⬆️
unittests	62.22% <ø> (+0.47%)	⬆️
unittests1	46.69% <ø> (-0.20%)	⬇️
unittests2	28.02% <ø> (+0.29%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

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

🚀 New features to boost your workflow:

• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.