refactor(adk): simplify tool reduction config, add truncation handler

[N3kox]

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[codecov]

Codecov Report

❌ Patch coverage is 75.81699% with 37 lines in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (alpha/08@95a1e79). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
adk/middlewares/reduction/reduction.go	75.81%	23 Missing and 14 partials ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             alpha/08     #776   +/-   ##
===========================================
  Coverage            ?   78.21%           
===========================================
  Files               ?      146           
  Lines               ?    19095           
  Branches            ?        0           
===========================================
  Hits                ?    14935           
  Misses              ?     3217           
  Partials            ?      943           

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