vehicle_level_test - null dmon_p pointer (and running into the player)

During (randomized order) testing, vehicle_level_test and vehicle_ramp_test_60 appear to have failed due to running into the player. Please see #46439 for further information; this is a separate issue to keep track of it independently.

Ping: @kevingranade, @jbytheway

Start by examining vehicle_level_test and vehicle_ramp_test_60, then read issue #46439 for the related failure details. Reproduce the randomized failures and trace the null dmon_p pointer and player collision; done means both tests run successfully without either failure.

Written by the indexing model from the issue text.