Add @ChangeId for CTS test

Because CTS tests must run on user builds, the compat change for testing
android.app.compat.CompatChanges must be a legitimate one, gated on
targetSdk.

Bug: 149340016
Test: atest CtsAppCompatHostTestCases # on user build

Change-Id: I49985681f2022308419f7f7a1e4e4d4c0fe48315