[WIP] Vae fusion improvements. #33540

Job	Run time
setup / setup	9s
runtime_small	2m 15s
runtime :: ubuntu-24.04	1m 15s
runtime :: windows-2022	3m 29s
runtime_tracing :: ubuntu-24.04 :: tracy	1m 19s
runtime :: macos-14	1m 21s
runtime_tracing :: ubuntu-24.04 :: console	1m 28s
runtime_tracing :: windows-2022 :: tracy	2m 39s
runtime_tracing :: windows-2022 :: console	2m 15s
runtime_tracing :: macos-14 :: console	1m 19s
linux_x64_bazel / linux_x64_bazel	19m 13s
linux_x64_clang / linux_x64_clang	16m 9s
linux_x64_clang_asan / linux_x64_clang_asan	20m 39s
ci_summary / summary	4s
	1h 13m 34s

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