deduplicate some e2e boilerplate setup.
Also, transitions exchange e2e tests from an in-
test loop over categories, to a well-defined test
func per category. The former design doesn't
play well with go test --run ./testName, and
causes all tests to run even if they don't match
the string.
---
#### Does this PR need a docs update or release note?
- [x] ⛔ No
#### Type of change
- [x] 🤖 Supportability/Tests
- [x] 🧹 Tech Debt/Cleanup
#### Test Plan
- [x] 💚 E2E
