Use -Zno-embed-metadata for the codegen backend and sysroot #4311

Job	Run time
test_llvm	3m 56s
bench	6m 10s
rustfmt	13s
dist (ubuntu-22.04, x86_64-unknown-linux-gnu)	1m 46s
dist (windows-latest, x86_64-pc-windows-gnu)	3m 9s
dist (macos-15-intel, x86_64-apple-darwin)	3m 17s
test (ubuntu-latest, x86_64-unknown-linux-gnu)	12m 1s
test (ubuntu-latest, s390x-unknown-linux-gnu, gcc-s390x-linux-gnu qemu-user)	4m 29s
dist (ubuntu-24.04-arm, aarch64-unknown-linux-gnu)	1m 38s
test (macos-latest, aarch64-apple-darwin)	12m 45s
dist (macos-latest, aarch64-apple-darwin)	1m 32s
test (macos-15-intel, x86_64-apple-darwin)	19m 48s
test (ubuntu-latest, riscv64gc-unknown-linux-gnu, gcc-riscv64-linux-gnu qemu-user)	4m 19s
test (windows-latest, x86_64-pc-windows-msvc)	18m 35s
test (windows-latest, x86_64-pc-windows-gnu)	26m 15s
test (ubuntu-24.04-arm, aarch64-unknown-linux-gnu)	9m 33s
dist (windows-latest, x86_64-pc-windows-msvc)	2m 8s
release	0s
	2h 11m 34s

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