fix: refactor log processing for improved clarity

[Itxaka]

• Moved log processing logic into a separate function processLogLines to enhance readability and maintainability.
• Simplified the log handling by reducing nested conditions and improving the flow of log message handling.
• Make sure if the installer is done, we still process the remaining logs to make the UI steps updated

[codecov]

Codecov Report

❌ Patch coverage is 0% with 47 lines in your changes missing coverage. Please review.
✅ Project coverage is 43.12%. Comparing base (cb5cb98) to head (51315d3).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
internal/agent/TUIinstallProcessPage.go	0.00%	47 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1003      +/-   ##
==========================================
+ Coverage   43.08%   43.12%   +0.04%     
==========================================
  Files          60       60              
  Lines        7726     7735       +9     
==========================================
+ Hits         3329     3336       +7     
- Misses       4070     4074       +4     
+ Partials      327      325       -2     

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