Update getUri helper to extract a single mongos node
Update getUri helper to extract a single mongos node

For most tests, we only want to expose a single mongos node to avoid issues with fail points. This change parses and reassembles the connection URI to only return a single mongos node in the URI.

mongodb/mongo-php-library,jmikola/mongo-php-library,mongodb/mongo-php-library,mongodb/mongo-php-library,jmikola/mongo-php-library,10gen-labs/mongo-php-library-prototype,jmikola/mongo-php-library,jmikola/mongo-php-library-prototype,mongodb/mongo-php-library,jmikola/mongo-php-library