Increase Battery level emergency shutdown time delay

from 300 ms to 60 seconds, to give enough time for the user to configure
the vehicle in the mean time.

This is needed especially when the battery cell count setting is wrong
(when it should be 3, but set to 4 for example), since then whenever you
boot the vehicle, it will shutdown after 300 ms, which leaves the user
puzzled as to exactly what's happening. And it also prevented the user
from changing the Parameter since it's shutting down so quickly.

60 second window is intended to be a reasonable time that will allow the
user to figure out what's going on (via checking the battery level on
QGC, etc) but also not deep discharge the battery to a dangerous level.

src/modules/commander/Commander.cpp

@@ -3967,8 +3967,8 @@ void Commander::battery_status_check()
 		if (_battery_warning == battery_status_s::BATTERY_WARNING_EMERGENCY) {
 #if defined(BOARD_HAS_POWER_CONTROL)
 
-			if (shutdown_if_allowed() && (px4_shutdown_request(400_ms) == 0)) {
-				mavlink_log_critical(&_mavlink_log_pub, "Dangerously low battery! Shutting system down\t");
+			if (shutdown_if_allowed() && (px4_shutdown_request(60_s) == 0)) {
+				mavlink_log_critical(&_mavlink_log_pub, "Dangerously low battery! Shutting system down in 60 seconds\t");
 				events::send(events::ID("commander_low_bat_shutdown"), {events::Log::Emergency, events::LogInternal::Warning},
 					     "Dangerously low battery! Shutting system down");