Fix streaming + tool bug in Ollama

[ekzhu]

Fix a bug that caused tool calls to be truncated in OllamaChatCompletionClient when streaming is on.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 77.24%. Comparing base (5508cc7) to head (26cfcc6).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6193      +/-   ##
==========================================
- Coverage   77.24%   77.24%   -0.01%     
==========================================
  Files         200      200              
  Lines       14217    14212       -5     
==========================================
- Hits        10982    10978       -4     
+ Misses       3235     3234       -1     

Flag	Coverage Δ
unittests	77.24% <ø> (-0.01%)	⬇️

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