Werk #16166: ibm storwize: Fix missing data when monitoring nodes

lsnodestats command was used for monitoring nodes in IBM Storwize devices. Storwize devices don't have the lsnodestats command which led to missing data in ibm_svc_nodestats services.

Now, the IBM SVC agent uses the lsnodestats if it's available and lsnodecanisterstats otherwise.

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