Fix CUJ_LAUNCHER_APP_CLOSE_TO_HOME Cuj for predictive back to home

CUJ_LAUNCHER_APP_CLOSE_TO_HOME was broken because in the non-fallback case, the anim on which addCujInstrumentation was called on was empty.

Bug: 300078127
Flag: com.android.window.flags.predictive_back_system_anims
Test: Manual, i.e. verifying that CUJ_LAUNCHER_APP_CLOSE_TO_HOME shows up properly in perfetto trace with the fix applied in the predictive back case
Change-Id: I4a1130bd7c4622c057db054d829f662a16443799