Change the performance metric key names in the Grafana Dashboards as per the changes made in Delfin

[anvithks]

Issue/Feature Description:
The performance metric key names have been updated in Delfin and the same needs to be changed in the default Grafana dashboards that are setup at the time of SRM toolchain installation.

Old metric name	unit	New metric name	unit
storage_response_time	ms	storage_responseTime	ms
storage_bandwidth	MBs	storage_throughput	MBs
storage_read_bandwidth	MBs	storage_readThroughput	MBs
storage_write_bandwidth	MBs	storage_writeThroughput	MBs
storage_throughput	MBs	storage_requests	IOPS
storage_read_throughput	MBs	storage_readRequests	IOPS
storage_write_throughput	MBs	storage_writeRequests	IOPS

Why this issue to fixed / feature is needed(give scenarios or use cases):
The performance metric key names are now different and the user will not be able to see any graphs if the Grafana dashboard does not know the metrics to display.

How to reproduce, in case of a bug:

Other Notes / Environment Information: (Please give the env information, log link or any useful information for this issue)