battery_params: increase default empty cellvoltage to 3.6v

Based on feedback that very often the battery is used down too low.
I observed this happens consistently when the cell voltage is properly
load compensated. The default load compensation before #19429 was very
inaccurate and resulted in unpredictable estimate.
After that if there is a usable current measurement and the battery is
within expected tolerances of the default internal resistance the
compensation is pretty good and 3.5V is too low for an empty compensated
cell voltage. That was seen in various logs where the compensated
cell voltage was already dropping fast after 3.6V.

In case the voltage is not load compensated the vehicle estimates the
state of charge a bit too low which is safer than to high
especially for a default configuration.

src/lib/battery/battery_params_deprecated.c

@@ -43,7 +43,7 @@
  * @group Battery Calibration
  * @category system
  */
-PARAM_DEFINE_FLOAT(BAT_V_EMPTY, 3.5f);
+PARAM_DEFINE_FLOAT(BAT_V_EMPTY, 3.6f);
 
 /**
  * This parameter is deprecated. Please use BAT1_V_CHARGED instead.

src/lib/battery/module.yaml

@@ -21,7 +21,7 @@ parameters:
             reboot_required: true
             num_instances: *max_num_config_instances
             instance_start: 1
-            default: [3.5, 3.5]
+            default: [3.6, 3.6]
 
         BAT${i}_V_CHARGED:
             description: