The client exposes a receiver method called RetryServerErrors which toggles a flag, c.retryServerErrors,
that enables/disables the retry logic in the http client. This means however, you could only enable
the retry logic once the client was created, meaning any failed metadata request in `NewClient()`
would not be retried. We've extended the interface of the client config object to allow
enabling `c.retryServerErrors` during client init `NewClient()`.