test_vtol_figure_eight: fix altitude check

wait_until_altitude() checks for absolute altitude being
close so checking for 1m below the setpoint can fail
if the speedup results in no sample inside the altitude
window being checked.

Ideally the test could check if the takeoff is done directly
instead of comparing altitudes in the first place.

test/mavsdk_tests/test_vtol_figure_eight.cpp

@@ -48,7 +48,7 @@ TEST_CASE("Figure eight execution clockwise", "[vtol]")
 	tester.arm();
 	tester.takeoff();
 	tester.wait_until_hovering();
-	tester.wait_until_altitude(takeoff_altitude - 1.f, std::chrono::seconds(60));
+	tester.wait_until_altitude(takeoff_altitude, std::chrono::seconds(30));
 	tester.transition_to_fixedwing();
 	tester.wait_until_fixedwing(std::chrono::seconds(5));
 	std::this_thread::sleep_for(std::chrono::seconds(1));
@@ -71,7 +71,7 @@ TEST_CASE("Figure eight execution counterclockwise", "[vtol]")
 	tester.arm();
 	tester.takeoff();
 	tester.wait_until_hovering();
-	tester.wait_until_altitude(takeoff_altitude - 1.f, std::chrono::seconds(60));
+	tester.wait_until_altitude(takeoff_altitude, std::chrono::seconds(30));
 	tester.transition_to_fixedwing();
 	tester.wait_until_fixedwing(std::chrono::seconds(5));
 	std::this_thread::sleep_for(std::chrono::seconds(1));