MEDIUM: applet: Set the conn-stream as appctx owner instead of the stream-int

Because appctx is now an endpoint of the conn-stream, there is no reason to
still have the stream-interface as appctx owner. Thus, the conn-stream is
now the appctx owner.
diff --git a/src/mworker.c b/src/mworker.c
index 5d30b18..e690f8b 100644
--- a/src/mworker.c
+++ b/src/mworker.c
@@ -509,7 +509,7 @@
 /*  Displays workers and processes  */
 static int cli_io_handler_show_proc(struct appctx *appctx)
 {
-	struct stream_interface *si = appctx->owner;
+	struct stream_interface *si = cs_si(appctx->owner);
 	struct mworker_proc *child;
 	int old = 0;
 	int up = now.tv_sec - proc_self->timestamp;