Fix cache gating

[wdykas]

What does this PR do ?

When cleaning up the PR from yesterday before merge I accidentally broke the performance improvement. Because we can eval every step in our inference code it was switching on the rebuilding the cache every step. We have fixed this and made sure the correct tensor is recorded during cuda graph building

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[wdykas]

/ok to test 6058614

[wdykas]

/ok to test da286c0

[wdykas]

/ok to test 972c7ad

[wdykas]

/ok to test 9d56ef9

[svcnvidia-nemo-ci]

🔄 Merge queue validation started!

You can track the progress here: https://github.com/NVIDIA/Megatron-LM/actions/runs/25017684832