Fix a outer loop iterates on item that is removed by inner loop problem.

updateForegroundApps() has the outer loop that iterate on mActiveForegroundApps,
but inside the loop stopAllForegroundServicesLocked() calls setServiceForegroundInnerLocked()
which calls decActiveForegroundAppLocked() to remove item from
mActiveForegroundApps, the end result is an ArrayIndexOutOfBoundsException.

Bug: 243841000
Test: build and run
Change-Id: Ia64816799fb7d36c481f382496c035e2ab85c2a3