DO NOT MERGE Disable example codec2-service by default

`android.hardware.media.c2@1.0-service` is an example codec2 service,
developers who wish to implement codec2 can use this code as a skeleton.

`android.hardware.media.c2@1.0-service` is not to be used directly
without customization. Mark it as "enabled: false" so it wouldn't affect
build.

Bug: 7456955
Bug: 159780061
Test: TH
Change-Id: I4a1acb4754b51c5d792dae3c96a4d6eaa5c01016