Disable cpp backend for android.hardware.vibrator

Disable CPP backend for vibrator HAL. Dependencies should use the
stable NDK instead.

This is also the recommended choice:

https://source.android.com/docs/core/architecture/aidl/aidl-hals#choosing-runtime

The HAL will be allowed to use ndk-stable types like PersistableBundle
after disabling the legacy CPP backend.

Fix: 349595412
Test: VtsHalVibratorTargetTest & VtsHalVibratorManagerTargetTest
Flag: EXEMPT NDK
Change-Id: Id5736e092afd36e786ecf3978ff6ad81c7a4df56