v1.14.1 - one World Bank retry ladder per snapshot

A World Bank outage now costs a country snapshot one retry ladder instead of two.

A snapshot calls the World Bank twice in sequence: once for the headline indicators, then again at the end of the debt indicator's source chain. The per-request host breaker exists so that a host which has already failed a full series of attempts is asked once more, not three more times, but the first call never reported to it. Measured with every upstream down: six World Bank fetches per snapshot before, four after, which is about 1.2 seconds less waiting. A single blip on the first call is still retried and recovered, and the other sources still get their own full series.

The test suite also stopped sleeping through retry backoff. Every attempt still happens in tests, only the wait is removed, and one test keeps the real schedule to prove production still pauses. Wall time fell from 24.8 seconds to 7.4 seconds on CI. No behaviour change from that part.