Update PermissionGroupChange for automotive

Find the allow button by text instead of id on automotive, as
it uses a standardized dialog for permissions.

Also cleanup an unnecessary function in BasePermissionTest

Fixes: 159033692
Test: make cts; cts-tradefed; run cts -m CtsPermissionTestCases -t android.permission.cts.PermissionGroupChange
Change-Id: I78bff95970293971e7cfd679a876cf0f4cf953cd
2 files changed