Limit CoredomainViolators test to Treble devices

This test does not need to be applied to non-Treble devices, such as
devices upgrading from N->O->P.

Bug: 122921510
Test: atest SELinuxHostTest#testCoredomainViolators
Change-Id: I13802d999b984a86740ac13fc45f560d504cc39b
Merged-In: Ia2cd9f1abfa4c457891b4fb8a1811da25a42b39e
1 file changed