Research spike: Investigating the failing tests on build

[pratishta]

Tests are failing on automatic builds on PRs, beginning with the merge commit from this PR. The failed build results in the same errors for all following PRs.

Built project successfully. Stored in "/home/runner/work/labs-zap-search/labs-zap-search/client/tmp/class-tests_dist-ArOLmUAq.tmp".
not ok 1 Chrome 131.0 - [undefined ms] - Global error: Uncaught ReferenceError: QUnit is not defined at http://localhost:7357/assets/test-support.js, line 9934
    ---
        browser log: |
            testContext: [object Object]
            ERROR: Uncaught ReferenceError: QUnit is not defined at http://localhost:7357/assets/test-support.js, line 9934
            
    ...
not ok 2 Chrome 131.0 - [undefined ms] - Global error: Uncaught Error: Could not find module `@ember/test-helpers` imported from `labs-zap-search/tests/test-helper` at http://localhost:7357/assets/vendor.js, line 252
    ---
        browser log: |
            WARN: DEPRECATION: Using `Ember.NAME_KEY` is deprecated, override `.toString` instead [deprecation id: ember-name-key-usage]
                    at logDeprecationStackTrace (http://localhost:7357/assets/vendor.js:55542:23)
                    at HANDLERS.<computed> (http://localhost:7357/assets/vendor.js:55636:11)
                    at raiseOnDeprecation (http://localhost:7357/assets/vendor.js:55569:11)
                    at HANDLERS.<computed> (http://localhost:7357/assets/vendor.js:55636:11)
                    at invoke (http://localhost:7357/assets/vendor.js:55648:11)
                    at deprecate (http://localhost:7357/assets/vendor.js:55607:30)
                    at Object.get (http://localhost:7357/assets/vendor.js:76289:50)
                    at Module.callback (http://localhost:7357/assets/vendor.js:216531:24)
                    at Module.exports (http://localhost:7357/assets/vendor.js:111:32)
            testContext: [object Object]
            ERROR: Uncaught Error: Could not find module `@ember/test-helpers` imported from `labs-zap-search/tests/test-helper` at http://localhost:7357/assets/vendor.js, line 252
            
    ...
not ok 3 Chrome 131.0 - [undefined ms] - Global error: Uncaught Error: Assertion Failed: The tests file was not loaded. Make sure your tests index.html includes "assets/tests.js". at http://localhost:7357/assets/vendor.js, line 55268
    ---
        browser log: |
            testContext: [object Object]
            ERROR: Uncaught Error: Assertion Failed: The tests file was not loaded. Make sure your tests index.html includes "assets/tests.js". at http://localhost:7357/assets/vendor.js, line 55268

The work in this ticket should:

• Find the code and commit that caused this build failure
• Investigate potential fixes without having to rollback