chore(Structure): remove script define symbols from project settings
chore(Structure): remove script define symbols from project settings

The Project Settings should not have any default script define symbols
as these should be automatically added by the SDK Manager.

gomez-addams/SteamVR_Unity_Toolkit,mattboy64/SteamVR_Unity_Toolkit,adamjweaver/VRTK,thestonefox/SteamVR_Unity_Toolkit,thestonefox/VRTK,gpvigano/VRTK,Innoactive/IA-unity-VR-toolkit-VRTK,TMaloteaux/SteamVR_Unity_Toolkit,gpvigano/SteamVR_Unity_Toolkit