fix: Enhance error handling tests and add service status checks

### Summary of Changes
- Introduced new tests for `handleRequestError` to cover various error scenarios including connection timeouts and service errors.
- Added tests for `determineServiceStatus` to verify service availability states.
- Updated `formatServiceData` and `formatEventData` tests to ensure correct formatting and handling of invalid data.

### Expected Results
- Improved coverage and reliability of error handling utilities tests, ensuring accurate error responses and service status checks.
- Enhanced maintainability of test code by applying clean code principles and better organization.

frontend/src/setupTests.js

@@ -0,0 +1,5 @@
+// jest-dom adds custom jest matchers for asserting on DOM nodes.
+// allows you to do things like:
+// expect(element).toHaveTextContent(/react/i)
+// learn more: https://github.com/testing-library/jest-dom
+import '@testing-library/jest-dom';