Explicitly declare allowPrivilegeEscalation to false

Although containers that do not run as privileged already have this set to false by kubernetes
Kubespace [asks us](https://hub.armo.cloud/docs/c-0016) to explicitly declare it to false where not needed.

Signed-off-by: Arthur Silva Sens <arthursens2005@gmail.com>

jsonnet/kube-prometheus/components/node-exporter.libsonnet

@@ -181,6 +181,9 @@ function(params) {
         { name: 'root', mountPath: '/host/root', mountPropagation: 'HostToContainer', readOnly: true },
       ],
       resources: ne._config.resources,
+      securityContext: {
+        allowPrivilegeEscalation: false,
+      },
     };
 
     local kubeRbacProxy = krp({