CASSJAVA-55 Remove setting "Host" header for metadata requests.

With some sysprops enabled this will actually be respected which completely borks Astra routing.

patch by Bret McGuire; reviewed by Alexandre Dutra and Bret McGuire for CASSJAVA-55

Author: absurdfarce

core/src/main/java/com/datastax/oss/driver/internal/core/config/cloud/CloudConfigFactory.java

@@ -229,7 +229,6 @@ protected BufferedReader fetchProxyMetadata(
       HttpsURLConnection connection = (HttpsURLConnection) metadataServiceUrl.openConnection();
       connection.setSSLSocketFactory(sslContext.getSocketFactory());
       connection.setRequestMethod("GET");
-      connection.setRequestProperty("host", "localhost");
       return new BufferedReader(
           new InputStreamReader(connection.getInputStream(), StandardCharsets.UTF_8));
     } catch (ConnectException e) {