Fix Nvidia device plugin that is running on CPU

**Description**

https://t.corp.amazon.com/P216481059

**Testing Done**

Will manually verify if plugin still crashes

Author: zhaoqizqwang

helm_chart/HyperPodHelmChart/values.yaml

@@ -138,6 +138,8 @@ nvidia-device-plugin:
       requiredDuringSchedulingIgnoredDuringExecution:
         nodeSelectorTerms: 
         - matchExpressions:
+          - key: nvidia.com/gpu
+            operator: Exists
           # nvidia plugin needs at least one node selector. Below label exists for all hyperpod nodes
           - key: kubernetes.io/os
             operator: In