Fix force-stop may restart stopped process

Assume the stopping package has 2 activities on top, when removing
the top one, if the next activity is not finishing, it will be
considered as visible and got started again. So before the removal,
all activities should be set as finishing.

Bug: 163048635
Test: ActivityManagerTest#testForceStopPackageWontRestartProcess
Change-Id: If84aa83607d33e3d18ed71713e85ff1de3ac7ab9