Make sure thought content is included in handoff context

[ekzhu]

Resolves #6295

Ensure the thought content gets included in handoff message conetxt, when the only tool call was handoff tool call.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 77.55%. Comparing base (165c189) to head (0f1ab93).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6319   +/-   ##
=======================================
  Coverage   77.55%   77.55%           
=======================================
  Files         202      202           
  Lines       14759    14761    +2     
=======================================
+ Hits        11446    11448    +2     
  Misses       3313     3313           

Flag	Coverage Δ
unittests	77.55% <100.00%> (+<0.01%)	⬆️

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