fix(translation): add translations missing in leftBar (#16741)

[CelineSebe]

Proposed changes

• add t_i18n

Related issues

• resolves fix(translations): threat translation in left menu #16741

How to test this PR

1- Take ne OCTI english version, ex: in french version, go to the left menu
2- Go to "menaces"

Checklist

• I consider the submitted work as finished
• I tested the code for its functionality
• I wrote test cases for the relevant use cases (coverage and e2e)
• I added/updated the relevant documentation (either on GitHub or on Notion)
• Where necessary, I refactored code to improve the overall quality

Further comments

Threat actors (individual) must be translated

[Copilot]

Pull request overview

This PR fixes the missing localization for the “Threat actors (individual)” entry in the left navigation menu by switching it from a hardcoded English label to the standard t_i18n(...) translation helper, aligning it with the other menu items.

Changes:

• Localize the “Threat actors (individual)” left-menu label using t_i18n(...).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 24.13%. Comparing base (4e88982) to head (38ba098).
⚠️ Report is 42 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #16744      +/-   ##
==========================================
+ Coverage   23.99%   24.13%   +0.13%     
==========================================
  Files        3268     3272       +4     
  Lines      173116   174665    +1549     
  Branches    42909    43810     +901     
==========================================
+ Hits        41541    42155     +614     
- Misses     131575   132510     +935     

Flag	Coverage Δ
opencti-client-python	46.30% <ø> (ø)
opencti-front	5.61% <ø> (+0.07%)	⬆️
opencti-graphql	66.83% <ø> (+0.26%)	⬆️

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[Archidoit]

Can you also add the translations for these 2 missings labels in LeftBar.tsx :