Updated caching to use functools

[teubert]

Small Change. Updating the caching feature in SimResult to use caching from internal functools

Generally using python features is preferred over implementing our own because it's often more efficient and reliable. Additionally, it's less logic to maintain.

Benchmarked change and it's about the same runtime (maybe slightly faster)

[github-actions]

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[lymichelle21]

LGTM - logically makes sense and passes test_sim_result

[kjjarvis]

Nice optimization. Tests run successfully