THRIFT-5453: Defer DNS from NewTSocketConf to TSocket.Open

Client: go

We used to do DNS lookups in NewTSocketConf, without any timeout checks.
Stop doing that and do DNS lookups in TSocket.Open instead, which
already checks for ConnectTimeout set in TConfiguration.

Also remove the error return from NewTSocketConf.
diff --git a/test/go/genmock.sh b/test/go/genmock.sh
index bccfdf3..27cd0c4 100644
--- a/test/go/genmock.sh
+++ b/test/go/genmock.sh
@@ -9,4 +9,4 @@
 
 `go env GOPATH`/bin/mockgen -build_flags "-mod=mod" -destination=src/common/mock_handler.go -package=common github.com/apache/thrift/test/go/src/gen/thrifttest ThriftTest
 
-rm -Rf $GOPATH
+chmod a+w -R $GOPATH && rm -Rf $GOPATH