Set battery charge custom start charging in percent.
Battery starts charging when it depletes the battery charge custom start charging value.
DeviceBatteryChargeCustomStartCharging must be at least five percentage points below DeviceBatteryChargeCustomStopCharging.
This policy is only used if DeviceBatteryChargeMode is set to "custom".
If this policy is not configured or left unset, the "standard" battery charge mode will be applied.