Align SplitDivider layer name for AppPairs flicker test

Test: atest com.android.wm.shell.flicker.apppairs
Test: go/wm-tests-flicker should become green
Fixes: 175230170
Bug: 172704238
Change-Id: I210430a9f36fe8aca43bc0e97d29b5530c9dcb28
3 files changed