Use -Zno-embed-metadata for the codegen backend and sysroot #1649

Job	Run time
abi_cafe (macos-latest, aarch64-apple-darwin)	4m 40s
abi_cafe (ubuntu-latest, x86_64-unknown-linux-gnu)	4m 37s
abi_cafe (ubuntu-24.04-arm, aarch64-unknown-linux-gnu)	3m 36s
abi_cafe (windows-latest, x86_64-pc-windows-msvc)	9m 51s
abi_cafe (macos-15-intel, x86_64-apple-darwin)	10m 32s
	33m 16s

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