Fix TaskFragmentTrustedModeTest

This CL removes the check to verify if Activity does not exist
because it is started to Task instead after [1].

Test: atest TaskFragmentTrustedModeTest TaskFragmentOrganizerTest
Test: atest TaskFragmentOrganizerPolicyTest SplitActivityLifecycleTest
Fixes: 238054859
Bug: 233578672

[1]: b4bf0a8550911e3504cebf121062debdb1094f9e

Merged-In: I60bf16544da340c8846ae5007ce73ed7415eb974
Change-Id: I60bf16544da340c8846ae5007ce73ed7415eb974
1 file changed