flutter-cluster-dashboard: fix KVM demo configurations

While reviewing things to document them, I realized thath the
flutter-cluster-dashboard configuration for the plain KVM demo
image was incorrect, and that a separate configuration was
required for the preconfigured demo image where the databroker
runs on the KVM host.  This fixes the existing configuration
file, adds a new one, and updates the corresponding preconfigured
guest image.

Bug-AGL: SPEC-5138

Change-Id: Ib24d3e1e5018efffce1bc820a7fd4f26ac38ddd6
Signed-off-by: Scott Murray <scott.murray@konsulko.com>
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/c/AGL/meta-agl-demo/+/29926
ci-image-build: Jenkins Job builder account
ci-image-boot-test: Jenkins Job builder account
Tested-by: Jenkins Job builder account