[Stream][NFC] Remove unnecessary IRs from specialize_encodings.mlir (… #34883

Job	Run time
setup / setup	8s
runtime_small	2m 30s
runtime :: ubuntu-24.04	1m 34s
runtime :: windows-2022	2m 36s
runtime :: macos-14	1m 28s
runtime_tracing :: ubuntu-24.04 :: tracy	1m 13s
runtime_tracing :: ubuntu-24.04 :: console	1m 15s
runtime_tracing :: windows-2022 :: tracy	2m 44s
runtime_tracing :: windows-2022 :: console	2m 35s
runtime_tracing :: macos-14 :: tracy	1m 17s
runtime_tracing :: macos-14 :: console	1m 1s
linux_x64_bazel / linux_x64_bazel	20m 15s
linux_x64_clang / linux_x64_clang	8m 19s
linux_x64_clang_asan / linux_x64_clang_asan	13m 48s
ci_summary / summary	2s
	1h 0m 45s

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