Move test_helper_utils to tests folder

The helper is supposed to only be used by tests, and it's used by several tests around the codebase, so let's have it in a shared location and make it clear it's only for tests

Also fix class as namespace issues and refactor helper code

Bug: 311642700
Test: npm run test:unit:ci
Flag: EXEMPT EXEMPT
Change-Id: Ieb841924d6682a764675dd89e9799c9ff14ca00a