Crash, if map is started twice without the VA server

My student worker found a happening bug in VA plugin when loading a map twice without the VA server. The first time everything works as expected, but the second time it crashes at: DisplayClusterEventWrapper.h:99 with The event was not atatched..

This is caused by SetUseVA(true) in VAPlugin.cpp:155 senden userVA = true at VAPlguin.cpp:1271.

Altough it involves not starting the VA server, I still consider it a bug, since the editor sessions should be state-less and at least my debugging / development process often includes not starting the VA server, if not needed, to save time.

This bug can be easily reproduced by eg loading the FaceAnimation map of the Character Plugin Test project. Interestingly, it does not occur when loading maps via OpenLevel, as it is the case with the showcase maps in this project.