Explicitly add CA certificate package to cluster images

Explicitly add CA certificate package to cluster images

Explicitly add kuksa-certificates-ca-agl to the cluster demo images so
it will be included in both regular and agl-demo-preload builds.  Also
remove obsolete dependency on kuksa-val-certificates-client from the
cluster-dashboard recipe.  These changes fix the regular vs
agl-demo-preload behavior for the agl-cluster-demo-platform build.

Bug-AGL: SPEC-4986

Change-Id: I62b1d976c66824fde50a3effdcdd34b428e82d54
Signed-off-by: Scott Murray <scott.murray@konsulko.com>
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/c/AGL/meta-agl-demo/+/29472
ci-image-build: Jenkins Job builder account
Reviewed-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>
ci-image-boot-test: Jenkins Job builder account
Tested-by: Jenkins Job builder account
(cherry picked from commit b5ca98fe204a7ec6f4a1cf84c19ffeb5f4deb128)
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/c/AGL/meta-agl-demo/+/29365
Tested-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>