Revert "fix(connection): unref the "_waitForConnect""

Author: vkarpov15

lib/connection.js

@@ -842,11 +842,6 @@ Connection.prototype._waitForConnect = async function _waitForConnect() {
           },
           bufferTimeoutMS
         );
-
-        // dont cause this timeout to keep the js process alive
-        if ('unref' in timeout) {
-          timeout.unref();
-        }
       })
     ]);