Mission yawing timeout in mission not working

[sfuhrer]

Describe the bug
When MIS_YAW_TMT is set to something >0, the expected behavior is that for a waypoint with enforced heading, the vehicle tries to align with the yaw setpoint for the time set in MIS_YAW_TMT, and otherwise aborts the mission. This feature is necessary for VTOLs during front transition, as we then want a heading enforced (not transitioning in arbitrary direction), but yaw authority on a VTOL is usually limited in windy conditions.
If the current mission is aborted, the user should then plan a new one where the transition points into the wind.

To Reproduce
Set MIS_YAW_TMT to something !=0.
Plan mission with (seperate) VTOL transition (not VTOL takeoff, as then heading is not enforced).
(In sitl, when MIS_YAW_TMT is set to 1 and the vehicle has to turn eg 90°, it should abort as it doesn't manage that in 1s)

Expected behavior
Abort mission when the vehicle can't align with yaw setpoint at transition point within MIS_YAW_TMT.

Additional context
I think that the problem is that the counter responsible for measuring the yawing time at the transition wp gets reset all the time, and thus does never reach above MIS_YAW_TMT. It gets reset because _waypoint_position_reached is reset to false after every time is_mission_item_reached() is executed (mission_block.cpp). This seems to have been introduced with #4992

[sfuhrer]

fixed with #12630