fix: address PR review feedback for k3s-azure-fleet playground

- Convert ALL_MEMBERS from string to bash array to prevent word-splitting
  and glob expansion issues when passing cluster names to joinMC.sh
- Remove fleet-networking installation since Istio handles all cross-cluster
  networking (mTLS, service discovery, east-west traffic) per reviewer feedback
- Clean up unused FLEET_NET_DIR variable and trap

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: German

documentdb-playground/k3s-azure-fleet/setup-fleet.sh

@@ -33,22 +33,21 @@ for cmd in kubectl helm git jq curl; do
 done
 
 # Get all member clusters (hub is also a member + k3s clusters)
-ALL_MEMBERS="$HUB_CLUSTER_NAME"
+ALL_MEMBERS=("$HUB_CLUSTER_NAME")
 
 # Add k3s clusters from deployment info
 IFS=' ' read -ra K3S_REGION_ARRAY <<< "$K3S_REGIONS"
 for region in "${K3S_REGION_ARRAY[@]}"; do
   if kubectl config get-contexts "k3s-$region" &>/dev/null; then
-    ALL_MEMBERS="$ALL_MEMBERS k3s-$region"
+    ALL_MEMBERS+=("k3s-$region")
   fi
 done
 
-echo "Members to join: $ALL_MEMBERS"
+echo "Members to join: ${ALL_MEMBERS[*]}"
 
 # Clone KubeFleet repository
 KUBFLEET_DIR=$(mktemp -d)
-FLEET_NET_DIR=""
-trap 'rm -rf "$KUBFLEET_DIR" "$FLEET_NET_DIR"' EXIT
+trap 'rm -rf "$KUBFLEET_DIR"' EXIT
 
 echo ""
 echo "Cloning KubeFleet repository..."
@@ -94,73 +93,13 @@ echo "✓ Hub-agent installed"
 echo ""
 echo "Joining member clusters to fleet..."
 chmod +x ./hack/membership/joinMC.sh
-# Note: $ALL_MEMBERS is intentionally unquoted — joinMC.sh expects individual context names as separate args
-./hack/membership/joinMC.sh "$TAG" "$HUB_CLUSTER_NAME" $ALL_MEMBERS
+./hack/membership/joinMC.sh "$TAG" "$HUB_CLUSTER_NAME" "${ALL_MEMBERS[@]}"
 
 popd > /dev/null
 
-# Install fleet-networking
-echo ""
-echo "Setting up fleet-networking..."
-FLEET_NET_DIR=$(mktemp -d)
-if ! git clone --quiet https://github.com/Azure/fleet-networking.git "$FLEET_NET_DIR"; then
-    echo "ERROR: Failed to clone fleet-networking repository"
-    exit 1
-fi
-
-pushd "$FLEET_NET_DIR" > /dev/null
-
-NETWORKING_TAG=$(curl -s "https://api.github.com/repos/Azure/fleet-networking/tags" | jq -r '.[0].name')
-echo "Using fleet-networking version: $NETWORKING_TAG"
-
-# Install hub-net-controller-manager
-kubectl config use-context "$HUB_CLUSTER_NAME"
-echo "Installing hub-net-controller-manager..."
-
-helm upgrade --install hub-net-controller-manager ./charts/hub-net-controller-manager/ \
-  --set fleetSystemNamespace=fleet-system-hub \
-  --set leaderElectionNamespace=fleet-system-hub \
-  --set image.tag=$NETWORKING_TAG \
-  --wait || echo "Warning: hub-net-controller-manager installation may have issues"
-
-HUB_CLUSTER_ADDRESS=$(kubectl config view -o jsonpath="{.clusters[?(@.name==\"$HUB_CLUSTER_NAME\")].cluster.server}")
-
-# Install networking on each member
-for MEMBER_CLUSTER in $ALL_MEMBERS; do
-  echo ""
-  echo "Installing fleet-networking on $MEMBER_CLUSTER..."
-  
-  kubectl config use-context "$MEMBER_CLUSTER"
-  
-  # Apply CRDs
-  kubectl apply -f config/crd/ 2>/dev/null || true
-  
-  # Install mcs-controller-manager
-  helm upgrade --install mcs-controller-manager ./charts/mcs-controller-manager/ \
-    --set refreshtoken.repository=$REGISTRY/refresh-token \
-    --set refreshtoken.tag=$FLEET_TAG \
-    --set image.tag=$NETWORKING_TAG \
-    --set image.pullPolicy=Always \
-    --set refreshtoken.pullPolicy=Always \
-    --set config.hubURL=$HUB_CLUSTER_ADDRESS \
-    --set config.memberClusterName=$MEMBER_CLUSTER \
-    --set enableV1Beta1APIs=true \
-    --set logVerbosity=5 || echo "Warning: mcs-controller-manager may have issues on $MEMBER_CLUSTER"
-  
-  # Install member-net-controller-manager
-  helm upgrade --install member-net-controller-manager ./charts/member-net-controller-manager/ \
-    --set refreshtoken.repository=$REGISTRY/refresh-token \
-    --set refreshtoken.tag=$FLEET_TAG \
-    --set image.tag=$NETWORKING_TAG \
-    --set image.pullPolicy=Always \
-    --set refreshtoken.pullPolicy=Always \
-    --set config.hubURL=$HUB_CLUSTER_ADDRESS \
-    --set config.memberClusterName=$MEMBER_CLUSTER \
-    --set enableV1Beta1APIs=true \
-    --set logVerbosity=5 || echo "Warning: member-net-controller-manager may have issues on $MEMBER_CLUSTER"
-done
-
-popd > /dev/null
+# Note: fleet-networking is NOT installed because Istio handles all cross-cluster
+# networking (mTLS, service discovery, east-west traffic). Installing both would
+# create conflicting network configurations.
 
 # Verify fleet status
 echo ""
@@ -183,7 +122,7 @@ echo "✅ KubeFleet Setup Complete!"
 echo "======================================="
 echo ""
 echo "Hub: $HUB_CLUSTER_NAME"
-echo "Members: $ALL_MEMBERS"
+echo "Members: ${ALL_MEMBERS[*]}"
 echo ""
 echo "Commands:"
 echo "  kubectl --context $HUB_CLUSTER_NAME get membercluster"