Remove SensorCategory enum (#352)

This enumeration was not useful and potentially confusing. Sensors can
report different sensor metrics, and they could belong to several of
these categories simultaneously. This defeats the purpose of having
singular categories for sensors. We need to rethink how to categorize
sensors. Until then, having it does not add any value, and therefore it
has been removed.

closes #348

Author: tiyash-basu-frequenz

RELEASE_NOTES.md

@@ -45,6 +45,7 @@
     - The code `UNDERVOLTAGE_SHUTDOWN` has been removed in favour of `UNDERVOLTAGE`.
     - New diagnostic codes have been added to cover more cases, especially for inverters.
     - The codes have been renumbered.
+- Removed `SensorCategory` enum, since it was not useful and potentially confusing. Sensors can report different sensor metrics, and they could belong to several of these categories simultaneously. This defeats the purpose of having singular categories for sensors. We need to rethink how to categorize sensors. Until then, having it does not add any value, and therefore it has been removed.
 
 ## Bug Fixes
 

proto/frequenz/api/common/v1/microgrid/sensors/sensors.proto

@@ -15,33 +15,6 @@ import "frequenz/api/common/v1/microgrid/lifetime.proto";
 
 import "google/protobuf/timestamp.proto";
 
-// Enumerated sensor categories.
-enum SensorCategory {
-  // Unspecified
-  SENSOR_CATEGORY_UNSPECIFIED = 0;
-
-  // Thermometer (temperature sensor)
-  SENSOR_CATEGORY_THERMOMETER = 1;
-
-  // Hygrometer (humidity sensor)
-  SENSOR_CATEGORY_HYGROMETER = 2;
-
-  // Barometer (pressure sensor).
-  SENSOR_CATEGORY_BAROMETER = 3;
-
-  // Pyranometer (solar irradiance sensor).
-  SENSOR_CATEGORY_PYRANOMETER = 4;
-
-  // Anemometer (wind velocity and direction sensor).
-  SENSOR_CATEGORY_ANEMOMETER = 5;
-
-  // Accelerometers (acceleration sensor).
-  SENSOR_CATEGORY_ACCELEROMETER = 6;
-
-  // General sensors, which do not fall in any of the above categories
-  SENSOR_CATEGORY_GENERAL = 7;
-}
-
 // Enum to represent the various states that a sensor can be in.
 // This enum is unified across all sensor categories for consistency.
 enum SensorStateCode {
@@ -82,9 +55,6 @@ message Sensor {
   // An optional name for the sensor.
   string name = 3;
 
-  // The category of the sensor.
-  SensorCategory category = 4;
-
   // The sensor manufacturer.
   string manufacturer = 5;