Assorted auto-diff enhancements for increased performance & more streamlined auto-diff results #5485

Job	Run time
build (linux, debug, gcc, x86_64)	13m 44s
build (linux, release, gcc, x86_64)	16m 47s
build (linux, release, gcc, wasm)	14m 13s
build (macos, debug, clang, aarch64)	10m 48s
build (macos, release, clang, aarch64)	12m 37s
build (windows, debug, cl, x86_64)	15m 55s
build (windows, release, cl, x86_64)	13m 7s
build (linux, release, gcc, aarch64, smoke, false, self-hosted, Linux, ARM64, true)	6m 11s
	1h 43m 22s

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