Allow to preload home if it was died on top while locked

RWC#attachApplication no longer starts sleeping non-occluded
activities, because there is no explicit request.
E.g. while device is locked, the process of top activity is
died. And then a service started in the same process.

Now the behavior is consistent that only explicit activity request
can make the activity start rather than from random component. So
the specified case should handle by itself. Such as preloading home,
which should check whether the activity has attached to the process.

Bug: 335396307
Test: Turn off screen. Kill home process.
      Home activity should be restarted.
Change-Id: I83388a8cb2b7dd64748502b9576811d3cd18986a