DrmHalTest.OfflineLicenseStateTest: search keySetId

Search for key set id instead of simply checking the number of total
offline licenses.

Fix LOG_TAG & remove clearkey specific comments from generic plugin
tests.

Bug: 118402843
Test: VtsHalDrmV1_2TargetTest
Change-Id: I245007317c813d5a8585d0a4ee29816b8f51ad3c