🧹 Remove unused FileUtil.readFile method

[pascalre]

🎯 What: Removed the unused readFile method from the FileUtil class and its corresponding unit tests.
💡 Why: This improves maintainability and readability of the codebase by removing dead code.
✅ Verification:

• Verified that readFile was not used anywhere in the codebase (except for its own tests) using grep.
• Manually inspected the affected files (src/util/file-util.ts and src/test/suite/util/file-util.test.ts) and their consumers.
• Attempted to run the full test suite and linter, although they failed due to environment issues (missing dependencies and network failure for npm install).
  ✨ Result: A cleaner codebase with less dead code to maintain.

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PR created automatically by Jules for task 7287668804241570251 started by @pascalre

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[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud