meta-agl-core: remove connman cluster demo support

meta-agl-core: remove connman cluster demo support

Remove cluster demo support logic from connman bbappend, as it has
been moved to meta-agl-demo instead.  This improves the separation
of core vs demo configuration changes.

Bug-AGL: SPEC-3749

Signed-off-by: Scott Murray <scott.murray@konsulko.com>
Change-Id: Ica4113509a73def565b15e5067c5d7db0a6ecaf1
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/c/AGL/meta-agl/+/25893
Tested-by: Jenkins Job builder account <agl-jobbuilder@automotivelinux.org>
ci-image-build: Jenkins Job builder account <agl-jobbuilder@automotivelinux.org>
ci-image-boot-test: Jenkins Job builder account <agl-jobbuilder@automotivelinux.org>
Reviewed-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>