only install sample bookinfo on clusters in the mesh (#18950)
only install sample bookinfo on clusters in the mesh (#18950)

Update the multicluster sample script to only install bookinfo on the
clusters in the mesh.
istio/istio,smawson/istio,istio/istio,istio/istio,smawson/istio,smawson/istio,smawson/istio,istio/istio,istio/istio,smawson/istio,smawson/istio