Remove wrapper

- Removed wrapper.py
- Removed main.py
- modified radical-api.service to launch the gunicorn process directly.
- Removed exit code in update method.

routers/system.py

@@ -12,4 +12,4 @@ router = APIRouter()
 @router.post("/system/update")
 def update(access_token: APIKey = Depends(get_system_key)):
     output = subprocess.check_output(['git', 'pull'], encoding='utf-8')
-    sys.exit(26)  # exit with restart code
+    sys.exit()