fix(take): remove redundant stop() call

It is not necessary to call stop() inside TakeOperator._n, because TakeOperator._c will call
Stream._x tear down method which will call stop() on the Producer, which in this case is
TakeOperator.

src/core.ts

@@ -910,7 +910,6 @@ export class TakeOperator<T> implements Operator<T, T> {
     } else {
       u._n(t);
       u._c();
-      this._stop();
     }
   }