fix mcore ckpt resume for static quantizers and MSE export #4749

Job	Run time
pr-gate / check-file-changes	19s
pr-gate / wait-checks / wait	10m 45s
gpu-tests (gpu_trtllm, 30, tensorrt-llm/release:1.3.0rc12)	10m 50s
gpu-tests (gpu, 60, pytorch:26.03-py3)	55m 20s
gpu-tests (gpu_megatron, 45, nemo:26.04)	28m 9s
gpu-pr-required-check	2s
	1h 45m 25s

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