Fix failed while running same pair again

The exitSplit called while we launch the same split pair caused
it cannot enter split successful then lead to tests failed.

Add check isEnteringSplit check for that exitSplit.

Fix: 262595710
Test: atest NexusLauncherTests
Change-Id: I8666476ff76e3912542d30441b144c67baed9f38
1 file changed