Update writeFiles function to handle newline characters more accurately

[andy1li]

Issue

Currently, the setup echo commands treat "\n" as literal strings instead of newlines, when we wanted them to be interpreted as newlines.

Fix

Add '-e' flag to the echo commands.

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Fixture

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Note

Improve echo logging to correctly interpret newline escapes and update fixtures to match.

• Core (logging/utils):
  • Enhance writeFiles to choose echo flags based on newline usage:
    • Trailing newline only → echo.
    • Newlines within content → echo -e (with trailing) or echo -ne (without trailing).
• Fixtures:
  • Update internal/test_helpers/fixtures/{ash,bash}/pipelines/pass to reflect echo -e for multi-line setup writes.

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[github-actions]

Triggered a Github Actions job to update fixtures.

[github-actions]

Triggered a Github Actions job to update fixtures.

[andy1li]

Thanks to @feamcor for highlighting the issue!