Add new fields to metric_desc map for tool-mlxreg

[HughNhan]

Synopsis: Add "device" , "sensor_index", and "sensor_name" fields.

Test:

[root@dhcp-10-26-9-237 ~]# crucible get metric --source mlxreg --type power-watts --period 3DDD384E-4CBF-11F1-8193-FECD10CC4134 --breakout hostname,metric
*** NOTICE: Crucible is at least 1 commits behind.  See 'crucible repo info' for details. ***

Checking for httpd...appears to be running
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Resolving cdmq dependencies...
up to date in 697ms

Metric data retrieved from API server: http://localhost:3000/api/v1/metric-data

Available breakouts:  benchmark-name,benchmark-role,csid,cstype,device,endpoint-label,engine-id,engine-role,engine-type,hosted-by,osruntime,sensor_index,sensor_name,tool-name,userenv                                                                                                                                     

                                                                         10-05-2026
 source        type                                 hostname      metric   22:04:56
-----------------------------------------------------------------------------------
 mlxreg power-watts nvd-srv-22.nvidia.eng.rdu2.dc.redhat.com total-power     124.00
 mlxreg power-watts nvd-srv-22.nvidia.eng.rdu2.dc.redhat.com   vr0-power      17.03
 mlxreg power-watts nvd-srv-22.nvidia.eng.rdu2.dc.redhat.com   vr1-power      28.00
 mlxreg power-watts nvd-srv-23.nvidia.eng.rdu2.dc.redhat.com total-power     124.00
 mlxreg power-watts nvd-srv-23.nvidia.eng.rdu2.dc.redhat.com   vr0-power      18.00

[HughNhan]

@atheurer - Please give a look when you have a chance. Thanks