Unregistering HIDL interfaces breaks VTS

Based on some back and forth on the internal IDL discuss group, it
sounds like we can't unregister interfaces anymore if they're defined in
the manifest. The CAN interface behind the HIDL interface will still be
taken down correctly, but this will get rid of the failing attempt to
bring down the HIDL interface.

Bug: 213841914
Bug: 213843613
Test: VtsHalCanBusV1_0TargetTest
Test: VtsHalCanControllerV1_0TargetTest
Test: VtsHalCanBusVirtualV1_0TargetTest
Change-Id: Iae4d6a650c30adacdc7c51140e0295915b516833
(cherry picked from commit d349f1d5)