DeviceAdvancedBatteryChargeModeDayConfig timezone behavior

Clarify that local time zone is used for
DeviceAdvancedBatteryChargeModeDayConfig policy.

Bug: b:154476021
BYPASS_POLICY_COMPATIBILITY_CHECK=clarify timezone behavior

Change-Id: If0acfe4df982f1921bdac643f77abcad07810c53
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2206798Reviewed-by: Maksim Ivanov <emaxx@chromium.org>
Commit-Queue: Oleh Lamzin <lamzin@google.com>
Cr-Commit-Position: refs/heads/master@{#770045}

components/policy/resources/policy_templates.json

@@ -18741,8 +18741,14 @@
               'type': 'object',
               'properties': {
                 'day': { '$ref': 'WeekDay' },
-                'charge_start_time': { '$ref': 'Time' },
-                'charge_end_time': { '$ref': 'Time' }
+                'charge_start_time': {
+                  'description': '''Time when the device will start charging, interpreted in the device's local time zone.''',
+                  '$ref': 'Time'
+                },
+                'charge_end_time': {
+                  'description': '''Time when the device will stop charging, interpreted in the device's local time zone.''',
+                  '$ref': 'Time'
+                }
               }
             }
           }