detach compute before attaching, as k8s compute doesn't support update (Azure#3030)

* detach compute before attaching

* fix typo

* refine log

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Co-authored-by: Ubuntu <zetia@DevBox-zetia.1jltvvkrfgyuhl3llhmbyldkog.bx.internal.cloudapp.net>

Author: zetiaatgithub

infra/bootstrapping/sdk_helpers.sh

@@ -494,6 +494,9 @@ function setup_compute() {
     then
         echo_info "Cluster is already attached to workspace for the cluster: ${CLUSTER_NAME} as ${COMPUTE_NAME} in workspace:${WORKSPACE_NAME} under namespace: ${COMPUTE_NS}..."
     else
+        echo_info "Detach compute ${COMPUTE_NAME} in workspace:${WORKSPACE_NAME} first, as k8s compute doesn't support update" 
+        az ml compute detach --subscription "${SUBSCRIPTION_ID}" --resource-group "${RESOURCE_GROUP_NAME}" --workspace-name "${WORKSPACE_NAME}" --name "${COMPUTE_NAME}" -y || true
+
         echo_info "Attaching compute to workspace for the cluster: ${CLUSTER_NAME} as ${COMPUTE_NAME} in workspace:${WORKSPACE_NAME} under namespace: ${COMPUTE_NS}"
         ATTACH_COMPUTE=$(az ml compute attach \
                 --subscription "${SUBSCRIPTION_ID}" \