Also ignore QML2_IMPORT_PATH.

More secure.

part of CURA-8475

cura_app.py

@@ -17,6 +17,7 @@ import faulthandler
 import os
 if sys.platform != "linux":  # Turns out the Linux build _does_ use this, but we're not making an Enterprise release for that system anyway.
     os.environ["QT_PLUGIN_PATH"] = ""  # Security workaround: Don't need it, and introduces an attack vector, so set to nul.
+    os.environ["QML2_IMPORT_PATH"] = ""  # Security workaround: Don't need it, and introduces an attack vector, so set to nul.
 
 from PyQt5.QtNetwork import QSslConfiguration, QSslSocket