stream: give re-subscribe test a 10s timeout instead of 5s

In a local test it took 9.8s to complete.

Author: dynst

packages/stream/src/concat.spec.ts

@@ -287,5 +287,5 @@ describe("concat", () => {
     }, 6 * intervalDuration);
 
     return ret;
-  });
+  }, 10000);
 });