Webmock Helper: Don't break other test suites

## Scope

This changes the mocks in this gem to be less likely to break other project test suites that also use Webmock.

In addition this change makes it easier to add newly mocked API requests, and rejects requests to algolia.io that are not mocked.

We've been using this change happily at Product Hunt for the last few months, sorry that it took so long to propose it upstream :)