camera: Allow shutter sounds to be disabled from camera2 api

When using the connectLegacy binder interface (available only
through an @hide java api), then consider the camera to be in the
camera2 api legacy mode.

In legacy mode, allow disabling the shutter sound unconditionally.

Bug: 17109582
Change-Id: Ieb3fc61ff111d792cc657c018e278349c25472cf