cleanup debt that grew over time in tests

There were always some things that bothered me regarding some tap tests that I wrote:

- Some tests are using the global cache with mocked modules which can get messy, as the cache.json points to the address from the mock-registry.
- no centralized config for port/registry address makes it hard to switch the port/address, this grew over time with the number of tests
- Some tests wrote warnings to taps output when running npm run tap
- Bonus: convert an old test to use no network any more

I splitted every topic in a single commit for better readability, I can rebase if everything is ok.