Confirm if DLT and Audiomanager should be built and installed in AGL demo images

Currently, we build Audiomanager (and DLT as its dependency) because it's pulled from
agl-demo (see [this file|https://git.automotivelinux.org/AGL/meta-agl-demo/tree/recipes-core/packagegroups/packagegroup-ivi-common-core-multimedia.bbappend)

If Audio Manager is not explicitly required by other components, it's then useless to build it, install it and distribute it.

Note that even if removed from default demo images, it's still possible to build and install it on demand.

So we should first deter!mine if audiomanager is required for upcoming demos.