Ensure notif permission is granted before revoking

This prevents a crash due to revoking a permission that wasn't granted.
Ex: code under test revokes the permission itself.

Fixes: 220647524
Test: atest MultiuserHostsideIntegrationTests:com.android.test.multiuser.host.OpenAppTest#testChrome -- --abi x86_64
Change-Id: I2387e5073bf27c410542d4bca38df2a1d9e10c4d