Fix FalconNodeSensor defaults

[gpontejos]

This adds the missing default markers to accommodated for nested objects within the FalconNodeSensor Spec.
Operator log output from a Get() to the API when starting reconciliation for a new deployment when only falcon_api is set in the Spec:

{
    "controller": "falconnodesensor",
    "controllerGroup": "falcon.crowdstrike.com",
    "controllerKind": "FalconNodeSensor",
    "FalconNodeSensor": {
        "name": "falcon-node-sensor"
    },
    "namespace": "",
    "name": "falcon-node-sensor",
    "reconcileID": "1a539e00-6d1c-45c6-b1b8-a4f11c1c0039",
    "nodesensor.Spec": {
        "installNamespace": "falcon-system",
        "node": {
            "tolerations": [
                {
                    "key": "node-role.kubernetes.io/master",
                    "operator": "Exists",
                    "effect": "NoSchedule"
                },
                {
                    "key": "node-role.kubernetes.io/control-plane",
                    "operator": "Exists",
                    "effect": "NoSchedule"
                },
                {
                    "key": "node-role.kubernetes.io/infra",
                    "operator": "Exists",
                    "effect": "NoSchedule"
                }
            ],
            "nodeAffinity": {},
            "imagePullPolicy": "Always",
            "updateStrategy": {
                "type": "RollingUpdate",
                "rollingUpdate": {}
            },
            "terminationGracePeriod": 30,
            "serviceAccount": {},
            "disableCleanup": false,
            "resources": {
                "limits": {},
                "requests": {}
            },
            "backend": "bpf",
            "gke": {},
            "priorityClass": {},
            "advanced": {}
        },
        "falcon": {
            "apd": false,
            "trace": "none"
        },
        "falcon_api": {
            "cloud_region": "autodiscover",
            "client_id": "CLIENT_ID",
            "client_secret": "CLIENT_SECRET"
        }
    }
}