When Activity relaunched, the SplitController will receive
onActivityDestroyed and onActivityCreated.
Before, we always remove all the reference onActivityDestroyed, which
can accidentally remove split pair finish relationship. Now we only
do that when the activity is actually finishing.
Also do the following to make sure there is no other regression:
1. Replace the stored activity reference with activity token, so it
won't be changed when activity relaunched.
2. Update #getContainerWithActivity to first check pending appeared
activity to make sure it returns the correct container before the
server update.
Bug: 260301635
Test: atest WMJetpackUnitTests:SplitControllerTest
Test: atest WMJetpackUnitTests:TaskFragmentContainerTest
Change-Id: Ife6de66d22e336bb872a9fccbdf03562fe6e089d
8f22204338