commander: improve logic for ekf2 preflight check

With this change we prevent the case where arming silently fails within
the first 10 seconds after boot.

Also, we now set the sensors as healthy as soon as the ekf is healthy,
and don't wait 10 seconds without actually checking.

src/modules/commander/Arming/PreFlightCheck/PreFlightCheck.cpp

@@ -236,18 +236,19 @@ bool PreFlightCheck::preflightCheck(orb_advert_t *mavlink_log_pub, vehicle_statu
 	}
 
 	if (estimator_type == 2) {
-		bool ekf_healthy = false;
 
-		// don't report ekf failures for the first 10 seconds to allow time for the filter to start
-		if (time_since_boot > 10_s) {
+		const bool ekf_healthy = ekf2Check(mavlink_log_pub, status, false, report_failures) &&
+					 ekf2CheckSensorBias(mavlink_log_pub, report_failures);
 
-			ekf_healthy = ekf2Check(mavlink_log_pub, status, false, report_failures) &&
-				      ekf2CheckSensorBias(mavlink_log_pub, report_failures);
+		// For the first 10 seconds the ekf2 can be unhealthy, and we just mark it
+		// as not present.
+		// After that or if report_failures is true, we'll set the flags as is.
 
-			set_health_flags(subsystem_info_s::SUBSYSTEM_TYPE_AHRS, true, true, ekf_healthy, status);
+		if (!ekf_healthy && time_since_boot < 10_s && !report_failures) {
+			set_health_flags(subsystem_info_s::SUBSYSTEM_TYPE_AHRS, true, false, false, status);
 
 		} else {
-			set_health_flags(subsystem_info_s::SUBSYSTEM_TYPE_AHRS, true, false, false, status);
+			set_health_flags(subsystem_info_s::SUBSYSTEM_TYPE_AHRS, true, true, ekf_healthy, status);
 		}
 
 		failed |= !ekf_healthy;