HUE-8313 [core] Remove hardcoding to ImpersonationBackend when using embedded mode

desktop/core/src/desktop/settings.py

@@ -396,8 +396,6 @@ TIME_ZONE = desktop.conf.TIME_ZONE.get()
 
 if desktop.conf.DEMO_ENABLED.get():
   AUTHENTICATION_BACKENDS = ('desktop.auth.backend.DemoBackend',)
-elif desktop.conf.IS_EMBEDDED.get():
-  AUTHENTICATION_BACKENDS = ('desktop.auth.backend.ImpersonationBackend',)
 else:
   AUTHENTICATION_BACKENDS = tuple(desktop.conf.AUTH.BACKEND.get())