add unit tests for request_context.py

[indhumitha]

Description

Added direct unit test coverage for backend/secuscan/request_context.py.
The new tests verify:

• Generation of a request ID when no ID is provided.
• Caller-provided request ID overrides.
• Deterministic behavior by mocking uuid4() for predictable generated IDs.

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Related Issues

Closes #564

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Type of Change

Bug fix (non-breaking change that adds missing unit test coverage)

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How Has This Been Tested?

Ran the following command locally:
python -m pytest testing/backend/unit/test_request_context.py

Result:

• 3 tests collected
• 3 tests passed successfully.

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Checklist

• Code follows the project's existing style and testing conventions.
• Performed a self-review of the changes.
• Documentation changes are not required for this update.
• No additional warnings introduced by these changes.