Implement timer for removing out of bounds units

[50275]

Add a timer to remove out of bounds units every 2 seconds

[50275]

technically there is room for improvement

• start/stop timer upon game state change (trigger)
• use try-except just in case removing this unit crashes the game as sk originally warned. can't reproduce
• Instead of deleting units, move or respawn them at their last known position. (Requires ObjectMap data structure and additional knowledge.)