samples/cuda_core: remove duplicate EXIT_WAIVED in glInteropMipmapLod

The file already defined EXIT_WAIVED at module level; the extra
definition added near the imports created a duplicate that caused
test_core_sample_waivers_use_negotiated_exit_code to fail (expects
exactly one assignment).

Author: lijinf2

samples/cuda_core/glInteropMipmapLod/glInteropMipmapLod.py

@@ -93,8 +93,6 @@
 import sys
 import time
 
-EXIT_WAIVED = int(os.environ.get("CUDA_PYTHON_SAMPLE_WAIVER_EXIT_CODE", "2"))
-
 import numpy as np
 
 from cuda.core import (