Remove battery SOP variants from the Metrics enum

Battery SoPs should be fetched from the `Bound` object provided in the
`MetricSample` message. Hence, the `Metrics` enum should not contain
these SoP variants.

Signed-off-by: Tiyash Basu <[email protected]>

Author: tiyash-basu-frequenz

proto/frequenz/api/common/v1/metrics/metric_sample.proto

@@ -134,9 +134,7 @@ enum Metric {
   // General BMS metrics.
   METRIC_BATTERY_CAPACITY = 101;
   METRIC_BATTERY_SOC_PCT = 102;
-  METRIC_BATTERY_SOP_CHARGE = 103;
-  METRIC_BATTERY_SOP_DISCHARGE = 104;
-  METRIC_BATTERY_TEMPERATURE = 105;
+  METRIC_BATTERY_TEMPERATURE = 103;
 
   // General inverter metrics.
   METRIC_INVERTER_TEMPERATURE = 120;