reduce verbosity of retryablehttpclient

The default client appears to be pretty spammy and flood us with
debug messages about POST and GET requests, and honestly we don't really
need these or benefit from them, I don't think, so let's not.

internal_client.go

@@ -103,6 +103,7 @@ func WithClientRetryPeriod(period time.Duration) InternalClientOption {
 		rc.RetryWaitMin = min
 		rc.RetryMax = int(attempts)
 		rc.CheckRetry = retryWith400Policy
+		rc.Logger = logger.NopLogger
 		c.retryableClient = rc
 	}
 }